diff --git a/apps/as/src/entities/instl-sncn/api/instl-sncn-service.ts b/apps/as/src/entities/instl-sncn/api/instl-sncn-service.ts
index 29d15fcf0..dd7dccd7a 100644
--- a/apps/as/src/entities/instl-sncn/api/instl-sncn-service.ts
+++ b/apps/as/src/entities/instl-sncn/api/instl-sncn-service.ts
@@ -1,6 +1,7 @@
 import { client } from "@/shared/api";
 import { ENDPOINT } from "@/shared/config";
 import type {
+  InstlSncnApplySaveRequestDto,
   InstlSncnMng,
   InstlSncnMngSearchParams,
   InstlSncnMngService,
@@ -19,6 +20,14 @@ export class InstlSncnApiService implements InstlSncnMngService {
     const response = await client.get<InstlSncnMng>(`${ENDPOINT.AS_INSTL_SERVICE.INSTL_SNCN}/${id}`);
     return response.data;
   }
+
+  public async saveApply(payload: InstlSncnApplySaveRequestDto): Promise<string> {
+    const response = await client.post<string>(
+      `${ENDPOINT.AS_INSTL_SERVICE.INSTL_SNCN}/save-apply`,
+      payload,
+    );
+    return response.data;
+  }
 }
 
 export const InstlSncnApi = new InstlSncnApiService();
diff --git a/apps/as/src/entities/instl-sncn/index.ts b/apps/as/src/entities/instl-sncn/index.ts
index a85a145b5..5da39b459 100644
--- a/apps/as/src/entities/instl-sncn/index.ts
+++ b/apps/as/src/entities/instl-sncn/index.ts
@@ -1,7 +1,10 @@
 export { InstlSncnApi } from "./api/instl-sncn-service";
 export {
   INSTL_SNCN_REGISTER_SELECTION_KEY,
+  type InstlSncnApplySaveRequestDto,
+  type InstlSncnBizCstSaveRequestDto,
   type InstlSncnBzScaleSaveDto,
+  type InstlSncnCklstResultSaveDto,
   type InstlSncnMng,
   type InstlSncnMngSearchParams,
   type SpringPage,
diff --git a/apps/as/src/entities/instl-sncn/model/instl-sncn-interface.ts b/apps/as/src/entities/instl-sncn/model/instl-sncn-interface.ts
index 1bf43482f..0209bfef3 100644
--- a/apps/as/src/entities/instl-sncn/model/instl-sncn-interface.ts
+++ b/apps/as/src/entities/instl-sncn/model/instl-sncn-interface.ts
@@ -80,7 +80,24 @@ export interface InstlSncnBizCstSaveRequestDto {
   tstmDesignAmt: number;
 }
 
+/** 설치인가 신청 - 체크리스트 결과 저장 DTO(배열 원소) */
+export interface InstlSncnCklstResultSaveDto {
+  cklstSn: number;
+  cklstArtclSn: number;
+  cklstRvwSn: number;
+  selected: "Y" | "N" | null;
+}
+
+/** 설치인가 신청 - 통합 저장 요청 DTO */
+export interface InstlSncnApplySaveRequestDto {
+  instlSncnMng: InstlSncnMng;
+  bzScaleList: InstlSncnBzScaleSaveDto[];
+  bizCstList: InstlSncnBizCstSaveRequestDto[];
+  cklstResultList: InstlSncnCklstResultSaveDto[];
+}
+
 export interface InstlSncnMngService {
   getPage: (params: InstlSncnMngSearchParams) => Promise<SpringPage<InstlSncnMng>>;
   getById: (id: string) => Promise<InstlSncnMng>;
+  saveApply: (payload: InstlSncnApplySaveRequestDto) => Promise<string>;
 }
diff --git a/apps/as/src/pages/instl-sncn/ui/cnfm-regist-page.tsx b/apps/as/src/pages/instl-sncn/ui/cnfm-regist-page.tsx
index 128cae223..97fc032e7 100644
--- a/apps/as/src/pages/instl-sncn/ui/cnfm-regist-page.tsx
+++ b/apps/as/src/pages/instl-sncn/ui/cnfm-regist-page.tsx
@@ -1,6 +1,6 @@
 "use client";
 
-import { useEffect, useMemo, useState } from "react";
+import { useEffect, useMemo, useRef, useState } from "react";
 import { useRouter } from "next/navigation";
 
 import { useQuery } from "@tanstack/react-query";
@@ -13,7 +13,11 @@ import type { CnstpSeMngTreeDto } from "@/entities/cnstp";
 import { cnstpService } from "@/entities/cnstp";
 import {
   INSTL_SNCN_REGISTER_SELECTION_KEY,
+  InstlSncnApi,
+  type InstlSncnApplySaveRequestDto,
+  type InstlSncnBizCstSaveRequestDto,
   type InstlSncnBzScaleSaveDto,
+  type InstlSncnMng,
 } from "@/entities/instl-sncn";
 import { Button, Input } from "@common/components";
 
@@ -103,8 +107,9 @@ function CnfmRegistPage() {
   const [etcNoticeOpen, setEtcNoticeOpen] = useState(true);
 
   /* ── 체크리스트 ── */
-  type CheckResultVal = "Y" | "N" | "";
+  type CheckResultVal = "Y" | "N" | null;
   const [checkResults, setCheckResults] = useState<Record<string, CheckResultVal>>({});
+  const cklstRowRefs = useRef<Record<string, HTMLTableRowElement | null>>({});
 
   const { data: cklstTree = [] } = useQuery<CklstTreeNode[]>({
     queryKey: ["cklstTree", "INSTL", taskSeComCd],
@@ -159,7 +164,7 @@ function CnfmRegistPage() {
       const next: Record<string, CheckResultVal> = {};
       cklstRows.forEach((row) => {
         const key = cklstKey(row);
-        next[key] = prev[key] ?? "";
+        next[key] = prev[key] ?? null;
       });
       return next;
     });
@@ -181,9 +186,8 @@ function CnfmRegistPage() {
         cklstSn: row.cklstSn,
         cklstArtclSn: row.cklstArtclSn,
         cklstRvwSn: row.cklstRvwSn,
-        selected: checkResults[cklstKey(row)] ?? "",
-      }))
-      .filter((row) => row.selected !== "");
+        selected: checkResults[cklstKey(row)] ?? null,
+      }));
 
   /* ── 사업규모 (공종구분 트리 연동) ── */
   // cnstpSeCd → { bscPl, budgetReflct, thtiDsgn } 단일 map
@@ -277,6 +281,20 @@ function CnfmRegistPage() {
       [acntgSeCd]: { ...(prev[acntgSeCd] ?? emptyAmt()), [col]: val },
     }));
 
+  /** 총사업비 맵 -> 백엔드 저장용 배열 DTO 변환 */
+  const toBizCstSaveDtoList = (): InstlSncnBizCstSaveRequestDto[] =>
+    acntgTree
+      .filter((node) => leafSet.has(node.acntgSeCd))
+      .map((node) => {
+        const row = amtMap[node.acntgSeCd] ?? emptyAmt();
+        return {
+          acntgSeCd: node.acntgSeCd,
+          bscPlanAmt: num(row.bscPl),
+          bgtRfltAmt: num(row.budgetReflct),
+          tstmDesignAmt: num(row.thtiDsgn),
+        };
+      });
+
   /**
    * indAcntgSeCdNm 의 앞 공백 수를 파싱해 padding px 값으로 반환
    * (공백 4칸 = 1 depth = 1rem)
@@ -306,6 +324,7 @@ function CnfmRegistPage() {
 
   /* ── 검증 ── */
   function fnValidation(mode: "SAVE" | "PRESENTN") {
+    /*
     if (!bzNm.trim()) {
       alert("사업명을 입력하세요.");
       return false;
@@ -322,26 +341,96 @@ function CnfmRegistPage() {
       alert("개인정보 제공에 동의하셔야 제출이 가능합니다.");
       return false;
     }
+         
+       
+    // 체크리스트 사용 항목(Y) 중 미선택 항목이 있으면 진행 불가
+    const hasUncheckedChecklist = cklstRows.some(
+      (row) =>  !checkResults[cklstKey(row)],
+    );
+    if (hasUncheckedChecklist) {
+      alert("체크리스트를 모두 체크하세요.");
+      return false;
+    } 
+    // 저장 시: 사용 항목(Y)은 검토 결과가 반드시 예(Y)여야 함 
+   */
+    if (mode === "SAVE") {
+      const invalidYesRow = cklstRows.find(
+        (row) => row.bchckUseYn === "Y" && checkResults[cklstKey(row)] !== "Y",
+      );
+      if (invalidYesRow) {
+        const invalidKey = cklstKey(invalidYesRow);
+        const invalidRowEl = cklstRowRefs.current[invalidKey];
+        invalidRowEl?.scrollIntoView({ behavior: "smooth", block: "center" });
+        const yesRadio = invalidRowEl?.querySelector<HTMLInputElement>(
+          `input[name="chk_${invalidKey}"][value="Y"]`,
+        );
+        yesRadio?.focus();
+        alert(`${invalidYesRow.rvwCn} 검토내용은 예(Y)여야 합니다.`);
+        return false;
+      }
+    }
+
     return true;
   }
 
-  function handleSave() {
+  const toInstlSncnMngPayload = (prgrsSttsComCd: "SV" | "ST"): InstlSncnMng => ({
+    instlSncnDocNo: "",
+    dongId: "",
+    sidoNm: "",
+    sggNm: "",
+    chrgrNm: "",
+    instNm: "",
+    envoSeComCd: instlCnfmApr,
+    envoSeCdNm: "",
+    taskSeComCd,
+    taskSeCdNm: taskSeComCdNm,
+    bgtBizCd: "",
+    bgtAplyYr: "",
+    bizNm: bzNm,
+    bizBgngYr: bzBgngYr,
+    bizEndYr: bzEndYr,
+    bizCn: bzCn,
+    aplcntNm: "",
+    aplcntMblTelno: "",
+    aplcntOgdpNm: "",
+    aplcntEmlAddr: "",
+    dsgnrNm,
+    dsgnrTelno,
+    dsgnrOgdpNm: dsgnrPsitn,
+    dsgnrEmlAddr,
+    atchFileGroupId: "",
+    prgrsSttsComCd,
+    prgrsSttsCdNm: "",
+    regDt: "",
+    mdfcnDt: "",
+    rgtrNm: "",
+  });
+
+  async function handleSave() {
     if (!fnValidation("SAVE")) return;
-    const payload = {
-      taskSeComCd,
+    const payload: InstlSncnApplySaveRequestDto = {
+      instlSncnMng: toInstlSncnMngPayload("SV"), // 저장 시 진행상태는 SV (임시저장)
       bzScaleList: toBzScaleSaveDtoList(),
+      bizCstList: toBizCstSaveDtoList(),
       cklstResultList: toCklstSaveDtoList(),
-    }; 
-    void payload;
-    alert("저장(임시) API 연동 후 progrsSttus=SV 전송",JSON.stringify(payload, null, 2));
+    };
+
+    try {
+      const issuedDocNo = await InstlSncnApi.saveApply(payload);
+      alert(`저장되었습니다. 문서번호: ${issuedDocNo}`);
+    } catch (error) {
+      console.error("저장 API 호출 실패", error);
+      alert("저장 중 오류가 발생했습니다.");
+    }
   }
 
   function handleSubmit() {
     if (!fnValidation("PRESENTN")) return;
     const payload = {
-      taskSeComCd,
+      instlSncnMng: toInstlSncnMngPayload("ST"), 
       bzScaleList: toBzScaleSaveDtoList(),
-      cklstResultList: toCklstSaveDtoList(),
+      bizCstList: toBizCstSaveDtoList(),
+      cklstRvwRsltList: toCklstSaveDtoList(),
     };
     void payload;
     alert("제출 API 연동 후 progrsSttus=ST 전송");
@@ -812,7 +901,12 @@ function CnfmRegistPage() {
                   const rvwPaddingLeft = `${Math.max(0, row.treeLevel - 1) * 16 + 8}px`;
 
                   return (
-                    <tr key={key}>
+                    <tr
+                      key={key}
+                      ref={(el) => {
+                        cklstRowRefs.current[key] = el;
+                      }}
+                    >
                       <td className="text-center text-[1.2rem]">{row.cklstArtclNm}</td>
                       <td className="!text-left pl-2 text-[1.2rem] text-gray-600" style={{ paddingLeft: rvwPaddingLeft }}>
                         {row.treeLevel > 1 ? "└ " : ""}