diff --git a/apps/as/src/entities/elapr/api/elapr-dmnd-service.ts b/apps/as/src/entities/elapr/api/elapr-dmnd-service.ts
index 8b2e67fa2..368600110 100644
--- a/apps/as/src/entities/elapr/api/elapr-dmnd-service.ts
+++ b/apps/as/src/entities/elapr/api/elapr-dmnd-service.ts
@@ -1,17 +1,67 @@
 import { client } from "@/shared/api";
 import { ENDPOINT } from "@/shared/config";
+import type { PageResponse } from "@/shared/model";
 
 import type {
-  ElaprDmndResponse,
-  ElaprDmndSaveRequest,
+  ElaprDmndResponseDto,
+  ElaprDmndSaveRequestDto,
+  ElaprDmndSearchDto,
   ElaprDmndService,
+  ElaprDocPrgrsResponseDto,
 } from "../model/elapr-dmnd-interface";
 
-async function create(body: ElaprDmndSaveRequest): Promise<ElaprDmndResponse> {
-  const response = await client.post<ElaprDmndResponse>(ENDPOINT.AS_ELAPR_SERVICE.ELAPR_DMND, body);
+const BASE = ENDPOINT.AS_ELAPR_SERVICE.ELAPR_DMND;
+
+async function findPage(params: ElaprDmndSearchDto): Promise<PageResponse<ElaprDmndResponseDto>> {
+  const response = await client.get<PageResponse<ElaprDmndResponseDto>>(BASE, { params });
   return response.data;
 }
 
-export const ElaprDmndApi: ElaprDmndService = {
-  create,
-};
+async function findById(elaprDmndId: string): Promise<ElaprDmndResponseDto> {
+  const response = await client.get<ElaprDmndResponseDto>(`${BASE}/${elaprDmndId}`);
+  return response.data;
+}
+
+async function save(body: ElaprDmndSaveRequestDto): Promise<ElaprDmndResponseDto> {
+  const response = await client.post<ElaprDmndResponseDto>(BASE, body);
+  return response.data;
+}
+
+async function update(
+  elaprDmndId: string,
+  body: ElaprDmndSaveRequestDto,
+): Promise<ElaprDmndResponseDto> {
+  const response = await client.put<ElaprDmndResponseDto>(`${BASE}/${elaprDmndId}`, body);
+  return response.data;
+}
+
+async function updateStatus(
+  elaprDmndId: string,
+  atrzSttsComCd: string,
+): Promise<ElaprDmndResponseDto> {
+  const response = await client.put<ElaprDmndResponseDto>(`${BASE}/${elaprDmndId}/status`, null, {
+    params: { atrzSttsComCd },
+  });
+  return response.data;
+}
+
+async function remove(elaprDmndId: string): Promise<void> {
+  await client.delete(`${BASE}/${elaprDmndId}`);
+}
+
+async function findDocPrgrsByDocNo(elaprDocNo: string): Promise<ElaprDocPrgrsResponseDto[]> {
+  const response = await client.get<ElaprDocPrgrsResponseDto[]>(
+    `${BASE}/sanc/docprgrs/${elaprDocNo}`,
+  );
+  return response.data;
+}
+
+export const elaprDmndService = {
+  findPage,
+  findById,
+  save,
+  update,
+  updateStatus,
+  remove,
+  findDocPrgrsByDocNo,
+} satisfies ElaprDmndService;
diff --git a/apps/as/src/entities/elapr/api/queries.ts b/apps/as/src/entities/elapr/api/queries.ts
index 59a6bb91b..fae6a0d03 100644
--- a/apps/as/src/entities/elapr/api/queries.ts
+++ b/apps/as/src/entities/elapr/api/queries.ts
@@ -8,6 +8,7 @@ import type {
   ElaprAplnSaveRequest,
   ElaprAplnUpdateRequest,
 } from "../model/elapr-apln-interface";
+import type { ElaprDmndSaveRequestDto, ElaprDmndSearchDto } from "../model/elapr-dmnd-interface";
 import type {
   ElaprTmpltSaveRequest,
   ElaprTmpltSearchParams,
@@ -15,10 +16,12 @@ import type {
 } from "../model/elapr-tmplt-interface";
 
 import { elaprAplnService } from "./elapr-apln-service";
+import { elaprDmndService } from "./elapr-dmnd-service";
 import { elaprTmpltService } from "./elapr-tmplt-service";
 
 const elaprTmpltBaseKey = [ENDPOINT.AS_ELAPR_SERVICE.ELAPR_TMPLT] as const;
 const elaprAplnBaseKey = [ENDPOINT.AS_ELAPR_SERVICE.ELAPR_APLN] as const;
+const elaprDmndBaseKey = [ENDPOINT.AS_ELAPR_SERVICE.ELAPR_DMND] as const;
 
 export function useElaprTmpltPage(params: ElaprTmpltSearchParams) {
   return useQuery({
@@ -50,13 +53,8 @@ export function useUpdateElaprTmplt() {
   const queryClient = useQueryClient();
 
   return useMutation({
-    mutationFn: ({
-      elaprTmpltId,
-      body,
-    }: {
-      elaprTmpltId: string;
-      body: ElaprTmpltUpdateRequest;
-    }) => elaprTmpltService.update(elaprTmpltId, body),
+    mutationFn: ({ elaprTmpltId, body }: { elaprTmpltId: string; body: ElaprTmpltUpdateRequest }) =>
+      elaprTmpltService.update(elaprTmpltId, body),
     onSuccess: (_data, { elaprTmpltId }) => {
       queryClient.invalidateQueries({ queryKey: elaprTmpltBaseKey });
       queryClient.invalidateQueries({
@@ -99,12 +97,8 @@ export function useSaveMultiElaprApln() {
   const queryClient = useQueryClient();
 
   return useMutation({
-    mutationFn: ({
-      body,
-    }: {
-      body: ElaprAplnSaveRequest[];
-      elaprTmpltId: string;
-    }) => elaprAplnService.saveMulti(body),
+    mutationFn: ({ body }: { body: ElaprAplnSaveRequest[]; elaprTmpltId: string }) =>
+      elaprAplnService.saveMulti(body),
     onSuccess: (_data, { elaprTmpltId }) => {
       queryClient.invalidateQueries({ queryKey: elaprAplnBaseKey });
       queryClient.invalidateQueries({
@@ -118,13 +112,8 @@ export function useUpdateElaprApln() {
   const queryClient = useQueryClient();
 
   return useMutation({
-    mutationFn: ({
-      aplnId,
-      body,
-    }: {
-      aplnId: string;
-      body: ElaprAplnUpdateRequest;
-    }) => elaprAplnService.update(aplnId, body),
+    mutationFn: ({ aplnId, body }: { aplnId: string; body: ElaprAplnUpdateRequest }) =>
+      elaprAplnService.update(aplnId, body),
     onSuccess: (_data, { body, aplnId }) => {
       queryClient.invalidateQueries({ queryKey: elaprAplnBaseKey });
       queryClient.invalidateQueries({
@@ -141,12 +130,8 @@ export function useDeleteElaprApln() {
   const queryClient = useQueryClient();
 
   return useMutation({
-    mutationFn: ({
-      aplnId,
-    }: {
-      aplnId: string;
-      elaprTmpltId: string;
-    }) => elaprAplnService.remove(aplnId),
+    mutationFn: ({ aplnId }: { aplnId: string; elaprTmpltId: string }) =>
+      elaprAplnService.remove(aplnId),
     onSuccess: (_data, { elaprTmpltId }) => {
       queryClient.invalidateQueries({ queryKey: elaprAplnBaseKey });
       queryClient.invalidateQueries({
@@ -160,12 +145,8 @@ export function useReorderElaprApln() {
   const queryClient = useQueryClient();
 
   return useMutation({
-    mutationFn: ({
-      body,
-    }: {
-      body: ElaprAplnReorderRequest;
-      elaprTmpltId: string;
-    }) => elaprAplnService.reorder(body),
+    mutationFn: ({ body }: { body: ElaprAplnReorderRequest; elaprTmpltId: string }) =>
+      elaprAplnService.reorder(body),
     onSuccess: (_data, { elaprTmpltId }) => {
       queryClient.invalidateQueries({ queryKey: elaprAplnBaseKey });
       queryClient.invalidateQueries({
@@ -174,3 +155,78 @@ export function useReorderElaprApln() {
     },
   });
 }
+
+export function useElaprDmndPage(params: ElaprDmndSearchDto) {
+  return useQuery({
+    queryKey: [...elaprDmndBaseKey, "findPage", params],
+    queryFn: () => elaprDmndService.findPage(params),
+  });
+}
+
+export function useElaprDmnd(elaprDmndId: string | null | undefined) {
+  return useQuery({
+    queryKey: [...elaprDmndBaseKey, "findById", elaprDmndId],
+    queryFn: () => elaprDmndService.findById(elaprDmndId!),
+    enabled: Boolean(elaprDmndId),
+  });
+}
+
+export function useElaprDocPrgrsByDocNo(elaprDocNo: string | null | undefined) {
+  return useQuery({
+    queryKey: [...elaprDmndBaseKey, "findDocPrgrsByDocNo", elaprDocNo],
+    queryFn: () => elaprDmndService.findDocPrgrsByDocNo(elaprDocNo!),
+    enabled: Boolean(elaprDocNo),
+  });
+}
+
+export function useSaveElaprDmnd() {
+  const queryClient = useQueryClient();
+
+  return useMutation({
+    mutationFn: (body: ElaprDmndSaveRequestDto) => elaprDmndService.save(body),
+    onSuccess: () => {
+      queryClient.invalidateQueries({ queryKey: elaprDmndBaseKey });
+    },
+  });
+}
+
+export function useUpdateElaprDmnd() {
+  const queryClient = useQueryClient();
+
+  return useMutation({
+    mutationFn: ({ elaprDmndId, body }: { elaprDmndId: string; body: ElaprDmndSaveRequestDto }) =>
+      elaprDmndService.update(elaprDmndId, body),
+    onSuccess: (_data, { elaprDmndId }) => {
+      queryClient.invalidateQueries({ queryKey: elaprDmndBaseKey });
+      queryClient.invalidateQueries({
+        queryKey: [...elaprDmndBaseKey, "findById", elaprDmndId],
+      });
+    },
+  });
+}
+
+export function useUpdateElaprDmndStatus() {
+  const queryClient = useQueryClient();
+
+  return useMutation({
+    mutationFn: ({ elaprDmndId, atrzSttsComCd }: { elaprDmndId: string; atrzSttsComCd: string }) =>
+      elaprDmndService.updateStatus(elaprDmndId, atrzSttsComCd),
+    onSuccess: (_data, { elaprDmndId }) => {
+      queryClient.invalidateQueries({ queryKey: elaprDmndBaseKey });
+      queryClient.invalidateQueries({
+        queryKey: [...elaprDmndBaseKey, "findById", elaprDmndId],
+      });
+    },
+  });
+}
+
+export function useRemoveElaprDmnd() {
+  const queryClient = useQueryClient();
+
+  return useMutation({
+    mutationFn: (elaprDmndId: string) => elaprDmndService.remove(elaprDmndId),
+    onSuccess: () => {
+      queryClient.invalidateQueries({ queryKey: elaprDmndBaseKey });
+    },
+  });
+}
diff --git a/apps/as/src/entities/elapr/index.ts b/apps/as/src/entities/elapr/index.ts
index ad35ae13b..4b14ea0d9 100644
--- a/apps/as/src/entities/elapr/index.ts
+++ b/apps/as/src/entities/elapr/index.ts
@@ -1,5 +1,5 @@
 export { elaprAplnService } from "./api/elapr-apln-service";
-export { ElaprDmndApi } from "./api/elapr-dmnd-service";
+export { elaprDmndService } from "./api/elapr-dmnd-service";
 export { elaprTmpltService } from "./api/elapr-tmplt-service";
 export {
   useCreateElaprTmplt,
@@ -7,11 +7,18 @@ export {
   useDeleteElaprTmplt,
   useElaprApln,
   useElaprAplnPage,
+  useElaprDmnd,
+  useElaprDmndPage,
+  useElaprDocPrgrsByDocNo,
   useElaprTmplt,
   useElaprTmpltPage,
+  useRemoveElaprDmnd,
   useReorderElaprApln,
+  useSaveElaprDmnd,
   useSaveMultiElaprApln,
   useUpdateElaprApln,
+  useUpdateElaprDmnd,
+  useUpdateElaprDmndStatus,
   useUpdateElaprTmplt,
 } from "./api/queries";
 export {
@@ -25,7 +32,13 @@ export {
   type ElaprAplnService,
   type ElaprAplnUpdateRequest,
 } from "./model/elapr-apln-interface";
-export type { ElaprDmndSaveRequest } from "./model/elapr-dmnd-interface";
+export type {
+  ElaprDmndResponseDto,
+  ElaprDmndSaveRequestDto,
+  ElaprDmndSearchDto,
+  ElaprDmndService,
+  ElaprDocPrgrsResponseDto,
+} from "./model/elapr-dmnd-interface";
 export type {
   ElaprTmplt,
   ElaprTmpltSaveRequest,
diff --git a/apps/as/src/entities/elapr/model/elapr-dmnd-interface.ts b/apps/as/src/entities/elapr/model/elapr-dmnd-interface.ts
index 249d98bf9..f653249f2 100644
--- a/apps/as/src/entities/elapr/model/elapr-dmnd-interface.ts
+++ b/apps/as/src/entities/elapr/model/elapr-dmnd-interface.ts
@@ -1,22 +1,62 @@
-export interface ElaprDmndSaveRequest {
+import type { PageableParams, PageResponse } from "@/shared/model";
+
+/** 백엔드 ElaprDmndSaveRequestDto */
+export interface ElaprDmndSaveRequestDto {
   elaprDocNo: string;
   elaprTmpltId: string;
   dmndTtl: string;
   dmndCn: string;
 }
 
-export interface ElaprDmndResponse {
+/** 백엔드 ElaprDmndResponseDto */
+export interface ElaprDmndResponseDto {
   elaprDmndId: string;
+  rqstrUuid?: string;
   elaprDocNo: string;
   elaprTmpltId: string;
   dmndTtl: string;
   dmndCn: string;
   atrzSttsComCd: string;
-  rqstrUuid: string;
-  regDt: string;
-  updtDt: string;
+  atrzSttsComNm?: string;
+  dmndDt?: string;
+  updtDt?: string;
 }
 
-export interface ElaprDmndService {
-  create(body: ElaprDmndSaveRequest): Promise<ElaprDmndResponse>;
+/** 백엔드 ElaprDmndSearchDto + Pageable */
+export interface ElaprDmndSearchDto extends PageableParams {
+  rqstrUuid?: string;
+  atrzSttsComCd?: string;
+  dmndTtl?: string;
+  dmndDtStart?: string;
+  dmndDtEnd?: string;
+}
+
+/** 백엔드 ElaprDocPrgrsResponseDto */
+export interface ElaprDocPrgrsResponseDto {
+  elaprDocNo: string;
+  elaprDmndId: string;
+  elaprPrgrsId: string;
+  atrzSeqNo?: number;
+  atrzSeComCd: string;
+  atrzSeComNm?: string;
+  aprvrUuid?: string;
+  aprvrUuidNm?: string;
+  atrzPrgrsSttsComCd: string;
+  atrzPrgrsSttsComNm?: string;
+  rjctRsn?: string;
+  atrzDt?: string;
+  jbpsSeNm?: string;
+  jbgdSeNm?: string;
+  ognzNm?: string;
+}
+
+/** Controller public 메서드명·시그니처와 동일 */
+export interface ElaprDmndService {
+  findPage(params: ElaprDmndSearchDto): Promise<PageResponse<ElaprDmndResponseDto>>;
+  findById(elaprDmndId: string): Promise<ElaprDmndResponseDto>;
+  save(body: ElaprDmndSaveRequestDto): Promise<ElaprDmndResponseDto>;
+  update(elaprDmndId: string, body: ElaprDmndSaveRequestDto): Promise<ElaprDmndResponseDto>;
+  updateStatus(elaprDmndId: string, atrzSttsComCd: string): Promise<ElaprDmndResponseDto>;
+  remove(elaprDmndId: string): Promise<void>;
+  findDocPrgrsByDocNo(elaprDocNo: string): Promise<ElaprDocPrgrsResponseDto[]>;
 }
diff --git a/apps/as/src/pages/instl-sncn-old/ui/cnfm-view-page.tsx b/apps/as/src/pages/instl-sncn-old/ui/cnfm-view-page.tsx
index 1a54fb444..ce7468c32 100644
--- a/apps/as/src/pages/instl-sncn-old/ui/cnfm-view-page.tsx
+++ b/apps/as/src/pages/instl-sncn-old/ui/cnfm-view-page.tsx
@@ -12,7 +12,7 @@ import { PROXY_HOST } from "@/shared/config";
 import { formatFileSize } from "@/shared/lib/file-utils";
 import axios from "axios";
 import { processElaprPrgrs } from "@/entities/elapr/api/elapr-prgrs-service";
-import { ElaprDmndApi } from "@/entities/elapr/api/elapr-dmnd-service";
+import { elaprDmndService } from "@/entities/elapr";
 import { dayjs, useUserStore, useAlertStore } from "@/shared/lib";
 import { instlSncnService, type InstlSncnApplySaveRequestDto } from "@/entities/instl-sncn";
 import { client } from "@/shared/api";
@@ -206,8 +206,7 @@ function CnfmViewPage({ id }: { id: string }) {
         dmndTtl: det.bizNm /* "구례 하수도 처리시설 2026", */,
         dmndCn: det.bizCn /*"구례 발주 하수도 처리시설 사업 2026년도 진행분 결제 요청 입니다."*/,
       };
-      // ElaprDmndApi 서비스를 통해 백엔드 연동
-      await ElaprDmndApi.create(payload);
+      await elaprDmndService.save(payload);
       alert("결재자 지정(결재요청 등록)이 완료되었습니다.");
       try {
         await query.refetch();
diff --git a/apps/as/src/pages/instl-sncn/ui/components/elapr-approval-dialog.tsx b/apps/as/src/pages/instl-sncn/ui/components/elapr-approval-dialog.tsx
new file mode 100644
index 000000000..31fed4ccc
--- /dev/null
+++ b/apps/as/src/pages/instl-sncn/ui/components/elapr-approval-dialog.tsx
@@ -0,0 +1,223 @@
+"use client";
+
+import { useState } from "react";
+
+import { useQueryClient } from "@tanstack/react-query";
+import { AxiosError } from "axios";
+
+import { ENDPOINT } from "@/shared/config";
+import { useAlertStore } from "@/shared/lib";
+import { useElaprDocPrgrsByDocNo } from "@/entities/elapr";
+import { processElaprPrgrs } from "@/entities/elapr/api/elapr-prgrs-service";
+import {
+  Button,
+  cn,
+  Dialog,
+  DialogContent,
+  DialogFooter,
+  DialogHeader,
+  DialogTitle,
+  Skeleton,
+  Table,
+  TableBody,
+  TableCell,
+  TableHead,
+  TableHeader,
+  TableRow,
+  Textarea,
+} from "@common/components";
+
+import { getApproverStatus, sortByAtrzSeqNo } from "../../lib/approval-utils";
+
+interface ElaprApprovalDialogProps {
+  open: boolean;
+  onOpenChange: (open: boolean) => void;
+  elaprDocNo: string;
+  currentUserUuid: string;
+  onSuccess: () => void;
+}
+
+function ElaprApprovalDialog({
+  open,
+  onOpenChange,
+  elaprDocNo,
+  currentUserUuid,
+  onSuccess,
+}: ElaprApprovalDialogProps) {
+  const queryClient = useQueryClient();
+  const alert = useAlertStore((state) => state.setMessage);
+  const [rjctRsn, setRjctRsn] = useState("");
+  const [isProcessing, setIsProcessing] = useState(false);
+
+  const { data: elaprDocPrgrsList = [], isLoading } = useElaprDocPrgrsByDocNo(
+    open ? elaprDocNo : null,
+  );
+
+  const orderedApprovers = sortByAtrzSeqNo(elaprDocPrgrsList);
+
+  const currentUserPrgrs = elaprDocPrgrsList.find(
+    (row) => row.aprvrUuid === currentUserUuid && row.atrzPrgrsSttsComCd === "ATRZ_PRGRS_002",
+  );
+  const canApprove = Boolean(currentUserPrgrs?.elaprPrgrsId);
+
+  async function handleApprove() {
+    if (!currentUserPrgrs?.elaprPrgrsId) return;
+
+    setIsProcessing(true);
+    try {
+      await processElaprPrgrs(currentUserPrgrs.elaprPrgrsId, "ATRZ_PRGRS_003");
+      alert("결재가 완료되었습니다.");
+      queryClient.invalidateQueries({
+        queryKey: [ENDPOINT.AS_ELAPR_SERVICE.ELAPR_DMND, "findDocPrgrsByDocNo", elaprDocNo],
+      });
+      onSuccess();
+      onOpenChange(false);
+    } catch (error: unknown) {
+      let errorMessage = "";
+      if (error instanceof AxiosError) {
+        errorMessage = error.response?.data?.message ?? "";
+      } else {
+        errorMessage = "결재 처리 중 오류가 발생했습니다.";
+      }
+      alert(errorMessage);
+    } finally {
+      setIsProcessing(false);
+    }
+  }
+
+  async function handleReject() {
+    if (!currentUserPrgrs?.elaprPrgrsId) return;
+    if (!rjctRsn.trim()) {
+      alert("반려 사유를 입력해주세요.");
+      return;
+    }
+
+    setIsProcessing(true);
+    try {
+      await processElaprPrgrs(currentUserPrgrs.elaprPrgrsId, "ATRZ_PRGRS_004");
+      alert("반려 처리가 완료되었습니다.");
+      queryClient.invalidateQueries({
+        queryKey: [ENDPOINT.AS_ELAPR_SERVICE.ELAPR_DMND, "findDocPrgrsByDocNo", elaprDocNo],
+      });
+      onSuccess();
+      onOpenChange(false);
+    } catch (error: unknown) {
+      let errorMessage = "";
+      if (error instanceof AxiosError) {
+        errorMessage = error.response?.data?.message ?? "";
+      } else {
+        errorMessage = "반려 처리 중 오류가 발생했습니다.";
+      }
+      alert(errorMessage);
+    } finally {
+      setIsProcessing(false);
+    }
+  }
+
+  function handleClose() {
+    setRjctRsn("");
+    onOpenChange(false);
+  }
+
+  return (
+    <Dialog open={open} onOpenChange={handleClose}>
+      <DialogContent className="max-w-[72rem]" aria-describedby={undefined}>
+        <DialogHeader>
+          <DialogTitle>전자결재</DialogTitle>
+        </DialogHeader>
+
+        <div className="space-y-6">
+          <div>
+            <h4 className="mb-3 text-xl font-semibold">결재 진행 단계</h4>
+            {isLoading ? (
+              <div className="space-y-3">
+                <Skeleton className="h-12 w-full" />
+                <Skeleton className="h-32 w-full" />
+              </div>
+            ) : orderedApprovers.length === 0 ? (
+              <div className="text-center text-gray-500">결재 정보가 없습니다.</div>
+            ) : (
+              <div className="overflow-x-auto">
+                <Table variant="line">
+                  <TableHeader>
+                    <TableRow>
+                      {orderedApprovers.map((row) => (
+                        <TableHead key={String(row.elaprPrgrsId ?? row.atrzSeComCd)}>
+                          {row.atrzSeComNm ?? row.atrzSeComCd}
+                        </TableHead>
+                      ))}
+                    </TableRow>
+                  </TableHeader>
+                  <TableBody>
+                    <TableRow>
+                      {orderedApprovers.map((row) => {
+                        const status = row.atrzPrgrsSttsComCd ?? "";
+                        const st = getApproverStatus(status);
+
+                        return (
+                          <TableCell
+                            key={String(row.elaprPrgrsId ?? row.atrzSeComCd)}
+                            align="center"
+                          >
+                            <div className="flex items-center justify-center gap-2">
+                              <span
+                                className={cn(
+                                  "inline-flex items-center rounded-md px-2 py-1 text-base font-semibold",
+                                  st.badgeClass,
+                                )}
+                              >
+                                {st.label}
+                              </span>
+                              <span className="font-semibold">{row.aprvrUuidNm ?? "-"}</span>
+                            </div>
+                            <div className="mt-2 text-base text-gray-500">
+                              {row.ognzNm ?? ""}
+                              {row.jbpsSeNm || row.jbgdSeNm
+                                ? ` · ${row.jbpsSeNm ?? ""}${row.jbgdSeNm ? ` ${row.jbgdSeNm}` : ""}`
+                                : ""}
+                            </div>
+                          </TableCell>
+                        );
+                      })}
+                    </TableRow>
+                  </TableBody>
+                </Table>
+              </div>
+            )}
+          </div>
+
+          {canApprove && (
+            <div>
+              <h4 className="mb-3 text-xl font-semibold">반려 의견</h4>
+              <Textarea
+                value={rjctRsn}
+                onChange={(event) => setRjctRsn(event.target.value)}
+                placeholder="반려 시 사유를 입력하세요"
+                rows={4}
+                className="!text-xl"
+              />
+            </div>
+          )}
+        </div>
+
+        <DialogFooter>
+          <Button type="button" color="white" onClick={handleClose} disabled={isProcessing}>
+            취소
+          </Button>
+          {canApprove && (
+            <>
+              <Button color="red" onClick={handleReject} disabled={isProcessing}>
+                반려
+              </Button>
+              <Button onClick={handleApprove} disabled={isProcessing}>
+                결재
+              </Button>
+            </>
+          )}
+        </DialogFooter>
+      </DialogContent>
+    </Dialog>
+  );
+}
+
+export { ElaprApprovalDialog };
diff --git a/apps/as/src/pages/instl-sncn/ui/components/floating-action-buttons.tsx b/apps/as/src/pages/instl-sncn/ui/components/floating-action-buttons.tsx
index bbfbad7c6..12887ad89 100644
--- a/apps/as/src/pages/instl-sncn/ui/components/floating-action-buttons.tsx
+++ b/apps/as/src/pages/instl-sncn/ui/components/floating-action-buttons.tsx
@@ -7,7 +7,7 @@ import { useConfirm } from "@frontend-opensource/use-react-hooks";
 import { useQueryClient } from "@tanstack/react-query";
 
 import { useAlertStore, useUserStore } from "@/shared/lib";
-import { ElaprDmndApi, ElaprDmndSaveRequest, type ElaprTmplt } from "@/entities/elapr";
+import { type ElaprDmndSaveRequestDto, elaprDmndService, type ElaprTmplt } from "@/entities/elapr";
 import {
   type DocPrgrsUpdateRequestDto,
   type InstlSncnApplySaveRequestDto,
@@ -29,8 +29,9 @@ import {
   buildTechReviewReplyPayload,
   computeReviewStepChecklistProgress,
 } from "../../lib/checklist-utils";
-import { type ChecklistFormState, ROLE_TO_REVIEW_STEP } from "../../model/view-types";
+import { type ChecklistFormState } from "../../model/view-types";
 
+import { ElaprApprovalDialog } from "./elapr-approval-dialog";
 import { ElaprTmpltPickerDialog } from "./elapr-tmplt-picker-dialog";
 import { TextInputDialog } from "./text-input-dialog";
 
@@ -43,7 +44,7 @@ interface FloatingActionButtonsProps {
   checklistFormState: ChecklistFormState;
 }
 
-type ActiveDialog = "elaprTmplt" | "rjct" | "dmndSplmnt" | null;
+type ActiveDialog = "elaprTmplt" | "rjct" | "dmndSplmnt" | "elaprApproval" | null;
 
 function FloatingActionButtons({
   data,
@@ -212,8 +213,6 @@ function FloatingActionButtons({
   }
 
   async function handleRjctClick() {
-    if (!(await confirm("반려하시겠습니까?"))) return;
-
     const payload: DocPrgrsUpdateRequestDto = {
       docNo,
       docSeComCd,
@@ -257,8 +256,6 @@ function FloatingActionButtons({
       return;
     }
 
-    if (!(await confirm("검토결과를 회신하시겠습니까?"))) return;
-
     const payload = buildTechReviewReplyPayload(data, checklistFormState, "ENV", "EP", "CP");
 
     await executeAction({
@@ -308,6 +305,27 @@ function FloatingActionButtons({
     });
   }
 
+  async function handleRvwCmptnClick() {
+    const { percent } = computeReviewStepChecklistProgress(
+      data.cklstResultList ?? [],
+      checklistFormState.results,
+      "KECO",
+    );
+
+    if (percent !== 100) {
+      alert("모든 체크리스트 항목을 체크해야 검토완료가 가능합니다.");
+      return;
+    }
+
+    const payload = buildTechReviewReplyPayload(data, checklistFormState, "KECO", "TE", "CP");
+
+    await executeAction({
+      action: INSTL_SNCN_VIEW_BUTTON_ACTION.rvwCmptn,
+      request: payload,
+      successMessage: "검토완료 처리되었습니다.",
+    });
+  }
+
   function handleDmndSplmntClick() {
     setActiveDialog("dmndSplmnt");
   }
@@ -399,11 +417,7 @@ function FloatingActionButtons({
             </Button>
           )}
           {shouldShowButton(INSTL_SNCN_VIEW_BUTTON_ACTION.rvwCmptn) && (
-            <Button
-              color="green"
-              onClick={() => void executeAction({ action: INSTL_SNCN_VIEW_BUTTON_ACTION.rvwCmptn })}
-              disabled={isProcessing}
-            >
+            <Button color="green" onClick={handleRvwCmptnClick} disabled={isProcessing}>
               검토완료
             </Button>
           )}
@@ -413,18 +427,12 @@ function FloatingActionButtons({
             </Button>
           )}
           {shouldShowButton(INSTL_SNCN_VIEW_BUTTON_ACTION.atrzAprv) && (
-            <Button
-              onClick={() => void executeAction({ action: INSTL_SNCN_VIEW_BUTTON_ACTION.atrzAprv })}
-              disabled={isProcessing}
-            >
+            <Button onClick={() => setActiveDialog("elaprApproval")} disabled={isProcessing}>
               결재(승인)
             </Button>
           )}
           {shouldShowButton(INSTL_SNCN_VIEW_BUTTON_ACTION.atrzRply) && (
-            <Button
-              onClick={() => void executeAction({ action: INSTL_SNCN_VIEW_BUTTON_ACTION.atrzRply })}
-              disabled={isProcessing}
-            >
+            <Button onClick={() => setActiveDialog("elaprApproval")} disabled={isProcessing}>
               결재(회신)
             </Button>
           )}
@@ -453,6 +461,19 @@ function FloatingActionButtons({
         isSubmitting={isProcessing}
         onConfirm={(value) => void handleDmndSplmntConfirm(value)}
       />
+      <ElaprApprovalDialog
+        open={activeDialog === "elaprApproval"}
+        onOpenChange={(open) => setActiveDialog(open ? "elaprApproval" : null)}
+        elaprDocNo={data.detDto.instlSncnDocNo}
+        currentUserUuid={userInfo?.userUnqId ?? ""}
+        onSuccess={() => {
+          setActiveDialog(null);
+          alert("결재가 완료되었습니다.");
+          queryClient.invalidateQueries({
+            queryKey: instlSncnKeys.detail(instlSncnDocNo),
+          });
+        }}
+      />
     </>
   );
 }
@@ -549,9 +570,11 @@ async function handleRqstTechRvw(context: ActionHandlerContext): Promise<void> {
   }
 }
 
-async function handleDsgntRvwr(context: ActionHandlerContext<ElaprDmndSaveRequest>): Promise<void> {
+async function handleDsgntRvwr(
+  context: ActionHandlerContext<ElaprDmndSaveRequestDto>,
+): Promise<void> {
   try {
-    await ElaprDmndApi.create(context.request);
+    await elaprDmndService.save(context.request);
     context.onSuccess?.();
   } catch (error) {
     context.onError?.(error as Error);
@@ -569,9 +592,15 @@ async function handleRvwStrg(
   }
 }
 
-async function handleRvwCmptn(context: ActionHandlerContext): Promise<void> {
-  // TODO: 검토완료 API 호출
-  context.onSuccess?.();
+async function handleRvwCmptn(
+  context: ActionHandlerContext<InstlSncnApplySaveRequestDto>,
+): Promise<void> {
+  try {
+    await instlSncnService.techReview(context.data.detDto.instlSncnDocNo, context.request);
+    context.onSuccess?.();
+  } catch (error) {
+    context.onError?.(error as Error);
+  }
 }
 
 async function handleDmndSplmnt(context: ActionHandlerContext): Promise<void> {
diff --git a/apps/as/src/pages/instl-sncn/ui/instl-view-page.tsx b/apps/as/src/pages/instl-sncn/ui/instl-view-page.tsx
index 4fdf74fed..fb1bf5fa1 100644
--- a/apps/as/src/pages/instl-sncn/ui/instl-view-page.tsx
+++ b/apps/as/src/pages/instl-sncn/ui/instl-view-page.tsx
@@ -4,10 +4,7 @@ import { useUserStore } from "@/shared/lib";
 import { useInstlSncnDetail } from "@/entities/instl-sncn";
 import { Skeleton } from "@common/components";
 
-import {
-  EMPTY_CKLST_RESULT_LIST,
-  useChecklistFormState,
-} from "../lib/use-checklist-form-state";
+import { EMPTY_CKLST_RESULT_LIST, useChecklistFormState } from "../lib/use-checklist-form-state";
 
 import { FloatingActionButtons } from "./components/floating-action-buttons";
 import { AttachmentsSection } from "./sections/attachments-section";
diff --git a/apps/as/src/pages/instl-sncn/ui/sections/approval-info-section.tsx b/apps/as/src/pages/instl-sncn/ui/sections/approval-info-section.tsx
index 3da85e7f7..c94dd6b24 100644
--- a/apps/as/src/pages/instl-sncn/ui/sections/approval-info-section.tsx
+++ b/apps/as/src/pages/instl-sncn/ui/sections/approval-info-section.tsx
@@ -1,11 +1,10 @@
 "use client";
 
-import { Button } from "@common/components";
-
-import { processElaprPrgrs } from "@/entities/elapr/api/elapr-prgrs-service";
-import { ElaprDmndApi } from "@/entities/elapr/api/elapr-dmnd-service";
-import type { ElaprDocPrgrsClientResponseDto } from "@/entities/instl-sncn";
 import { dayjs, useAlertStore, useUserStore } from "@/shared/lib";
+import { elaprDmndService } from "@/entities/elapr";
+import { processElaprPrgrs } from "@/entities/elapr/api/elapr-prgrs-service";
+import type { ElaprDocPrgrsClientResponseDto } from "@/entities/instl-sncn";
+import { Button } from "@common/components";
 
 import { getApproverStatus, sortByAtrzSeqNo } from "../../lib/approval-utils";
 
@@ -42,9 +41,7 @@ function ApprovalInfoSection({
     const status = row.atrzPrgrsSttsComCd ?? "";
     const st = getApproverStatus(status);
     const canApprove =
-      status === "ATRZ_PRGRS_002" &&
-      row.elaprPrgrsId &&
-      userInfo?.userUnqId === row.aprvrUuid;
+      status === "ATRZ_PRGRS_002" && row.elaprPrgrsId && userInfo?.userUnqId === row.aprvrUuid;
 
     return (
       <div className="text-center">
@@ -90,7 +87,7 @@ function ApprovalInfoSection({
 
   const handleAssignApprover = async () => {
     try {
-      await ElaprDmndApi.create({
+      await elaprDmndService.save({
         elaprDocNo: docNo,
         elaprTmpltId: "TMPLT20260611000001",
         dmndTtl: docTitle,
@@ -117,10 +114,7 @@ function ApprovalInfoSection({
                     </th>
                   ))
                 : orderedApprovers.map((row) => (
-                    <th
-                      key={String(row.elaprPrgrsId ?? row.atrzSeComCd)}
-                      className="text-center"
-                    >
+                    <th key={String(row.elaprPrgrsId ?? row.atrzSeComCd)} className="text-center">
                       {row.atrzSeComNm ?? row.atrzSeComCd}
                     </th>
                   ))}
diff --git a/apps/as/src/pages/instl-sncn/ui/sections/checklist-section.tsx b/apps/as/src/pages/instl-sncn/ui/sections/checklist-section.tsx
index 050f14452..2f7e8dd74 100644
--- a/apps/as/src/pages/instl-sncn/ui/sections/checklist-section.tsx
+++ b/apps/as/src/pages/instl-sncn/ui/sections/checklist-section.tsx
@@ -14,6 +14,7 @@ import {
 import {
   type ChecklistFormState,
   REVIEW_STEP_LABELS,
+  ROLE_TO_REVIEW_STEP,
   TASK_CODE_LABELS,
 } from "../../model/view-types";
 import { ChecklistTaskPanel } from "../components/checklist-task-panel";
@@ -40,7 +41,8 @@ function ChecklistSection({
   );
   const taskCodes = useMemo(() => extractTaskCodes(cklstResultList), [cklstResultList]);
 
-  const [selectedReviewStep, setSelectedReviewStep] = useState<ReviewStepCode>("LOCAL");
+  const defaultReviewStep = ROLE_TO_REVIEW_STEP[userRoleCode ?? ""] ?? "LOCAL";
+  const [selectedReviewStep, setSelectedReviewStep] = useState<ReviewStepCode>(defaultReviewStep);
   const [selectedTaskCode, setSelectedTaskCode] = useState<string | null>(null);
 
   useEffect(() => {