diff --git a/apps/st/src/components/statistics/verification/ImrVerificationHistory.tsx b/apps/st/src/components/statistics/verification/ImrVerificationHistory.tsx
index 304fea591..a160cb203 100644
--- a/apps/st/src/components/statistics/verification/ImrVerificationHistory.tsx
+++ b/apps/st/src/components/statistics/verification/ImrVerificationHistory.tsx
@@ -1,6 +1,7 @@
 "use client";
 
-import { useEffect, useMemo, useState } from "react";
+import type { Dispatch, SetStateAction } from "react";
+import { useEffect, useMemo, useRef, useState } from "react";
 import { Line } from "react-chartjs-2";
 
 import { keepPreviousData, useQuery } from "@tanstack/react-query";
@@ -72,6 +73,7 @@ type DateRangeValue = {
 };
 
 const EMPTY_DATA: never[] = [];
+const REGION_ALL_VALUE = "ALL";
 
 function getImrDetailGridColumnInfo(statsCd: string): ColumnInfo {
     const visible =
@@ -96,6 +98,21 @@ function getVerificationYearOptions(): string[] {
     );
 }
 
+function applySingleOptionRegionDefault<T>(
+    list: T[] | undefined,
+    setValue: Dispatch<SetStateAction<string>>,
+    resolveValue: (item: T) => string,
+) {
+    if (!list || list.length !== 1) return;
+
+    const onlyItem = list[0];
+    if (!onlyItem) return;
+
+    setValue((prev) =>
+        prev === REGION_ALL_VALUE ? resolveValue(onlyItem) : prev,
+    );
+}
+
 const ImrVerificationHistory = () => {
     const yearOptions = useMemo(() => getVerificationYearOptions(), []);
     const defaultYear: string =
@@ -104,8 +121,9 @@ const ImrVerificationHistory = () => {
             : "";
 
     // Area A Search States
-    const [searchSido, setSearchSido] = useState<string>("");
-    const [searchSigungu, setSearchSigungu] = useState<string>("");
+    const [searchSido, setSearchSido] = useState<string>(REGION_ALL_VALUE);
+    const [searchSigungu, setSearchSigungu] =
+        useState<string>(REGION_ALL_VALUE);
     const [searchStatsYr, setSearchStatsYr] = useState<string>(defaultYear);
     const [searchStatsCd, setSearchStatsCd] = useState<string>("");
     const [dateRange, setDateRange] = useState<DateRangeValue | undefined>({
@@ -150,6 +168,28 @@ const ImrVerificationHistory = () => {
         gugunSkipYn: doList.includes(selectedSidoBsnmCd) ? "N" : "Y",
     });
     const sigunguOptions = sigunguData ?? [];
+    const allowRegionAutoDefaultRef = useRef(true);
+
+    useEffect(() => {
+        if (!allowRegionAutoDefaultRef.current) return;
+
+        applySingleOptionRegionDefault(
+            sidoData?.sidoList,
+            setSearchSido,
+            (item) => item.sido,
+        );
+    }, [sidoData?.sidoList]);
+
+    useEffect(() => {
+        if (!allowRegionAutoDefaultRef.current) return;
+        if (searchSido === REGION_ALL_VALUE) return;
+
+        applySingleOptionRegionDefault(
+            sigunguData,
+            setSearchSigungu,
+            (item) => item.gugun,
+        );
+    }, [sigunguData, searchSido]);
 
     const imrDetailColumnInfo = useMemo(
         () => getImrDetailGridColumnInfo(selectedHistory?.statsCd ?? ""),
@@ -248,12 +288,12 @@ const ImrVerificationHistory = () => {
             vrfcMthdCd: "IMR",
             sort: "anlsSn,desc",
         };
-        if (searchSido !== "") {
+        if (searchSido !== "" && searchSido !== REGION_ALL_VALUE) {
             const selectedSggBsnmCd = sigunguOptions.find(
                 (item) => item.gugun === searchSigungu,
             )?.bsnmCd;
             params.sewerBzmnCd =
-                searchSigungu !== ""
+                searchSigungu !== "" && searchSigungu !== REGION_ALL_VALUE
                     ? (selectedSggBsnmCd ?? "")
                     : selectedSidoBsnmCd;
         }
@@ -271,8 +311,9 @@ const ImrVerificationHistory = () => {
     };
 
     const handleReset = () => {
-        setSearchSido("");
-        setSearchSigungu("");
+        allowRegionAutoDefaultRef.current = false;
+        setSearchSido(REGION_ALL_VALUE);
+        setSearchSigungu(REGION_ALL_VALUE);
         setSearchStatsCd("");
         const defaultRange = {
             from: dayjs().subtract(1, "month").toDate(),
@@ -410,13 +451,16 @@ const ImrVerificationHistory = () => {
                             value={searchSido}
                             onValueChange={(val) => {
                                 setSearchSido(val);
-                                setSearchSigungu("");
+                                setSearchSigungu(REGION_ALL_VALUE);
                             }}
                         >
                             <SelectTrigger className="w-[14rem]">
-                                <SelectValue placeholder="시도 선택" />
+                                <SelectValue placeholder="전체" />
                             </SelectTrigger>
                             <SelectContent>
+                                <SelectItem value={REGION_ALL_VALUE}>
+                                    전체
+                                </SelectItem>
                                 {sidoOptions.map((opt) => (
                                     <SelectItem
                                         key={opt.adstDstrCd}
@@ -436,12 +480,18 @@ const ImrVerificationHistory = () => {
                         <Select
                             value={searchSigungu}
                             onValueChange={setSearchSigungu}
-                            disabled={searchSido === ""}
+                            disabled={
+                                searchSido === "" ||
+                                searchSido === REGION_ALL_VALUE
+                            }
                         >
                             <SelectTrigger className="w-[14rem]">
-                                <SelectValue placeholder="시군구 선택" />
+                                <SelectValue placeholder="전체" />
                             </SelectTrigger>
                             <SelectContent>
+                                <SelectItem value={REGION_ALL_VALUE}>
+                                    전체
+                                </SelectItem>
                                 {sigunguOptions.map((opt) => (
                                     <SelectItem
                                         key={opt.adstDstrCd}
diff --git a/apps/st/src/components/statistics/verification/StatisticsVerificationReport.tsx b/apps/st/src/components/statistics/verification/StatisticsVerificationReport.tsx
index c194541ad..0b0ac91b4 100644
--- a/apps/st/src/components/statistics/verification/StatisticsVerificationReport.tsx
+++ b/apps/st/src/components/statistics/verification/StatisticsVerificationReport.tsx
@@ -126,6 +126,8 @@ function useGridCheckboxSelection<T>(
     return { handleItemChecked, handleAllChecked };
 }
 
+const REGION_ALL_OPTION = { label: "전체", value: "ALL" };
+
 const DEFAULT_FILTERS: StatisticsVerificationFilterState = {
     ctpvNm: null,
     sggNm: null,
@@ -133,6 +135,8 @@ const DEFAULT_FILTERS: StatisticsVerificationFilterState = {
     sewerBzmnCd: null,
     statsCd: null,
     pbcpSbmsnSttsCd: null,
+    ctpvSewerBzmnCd: "ALL",
+    sggSewerBzmnCd: "ALL",
 };
 
 const DEFAULT_SUB_FILTERS: StatisticsVerificationSubFilterState = {
@@ -422,14 +426,25 @@ function StatisticsVerificationReport() {
 
             // 시도 변경 시
             if (key === "ctpvNm") {
-                setFilters((prev) => ({
-                    ...prev,
-                    sewerBzmnCd: value,
-                    ctpvNm: optionData?.label,
-                    ctpvSewerBzmnCd: value,
-                    sggNm: "",
-                    sggSewerBzmnCd: "",
-                }));
+                if (value === "ALL") {
+                    setFilters((prev) => ({
+                        ...prev,
+                        ctpvNm: null,
+                        sggNm: null,
+                        sewerBzmnCd: null,
+                        ctpvSewerBzmnCd: "ALL",
+                        sggSewerBzmnCd: "ALL",
+                    }));
+                } else {
+                    setFilters((prev) => ({
+                        ...prev,
+                        sewerBzmnCd: value,
+                        ctpvNm: optionData?.label,
+                        ctpvSewerBzmnCd: value,
+                        sggNm: null,
+                        sggSewerBzmnCd: "ALL",
+                    }));
+                }
                 setSubFilters((prev) => ({
                     ...prev,
                     ctpvNm: "",
@@ -441,12 +456,25 @@ function StatisticsVerificationReport() {
 
             // 시군구 변경 시
             if (key === "sggNm") {
-                setFilters((prev) => ({
-                    ...prev,
-                    sewerBzmnCd: value,
-                    sggNm: optionData?.label,
-                    sggSewerBzmnCd: value,
-                }));
+                if (value === "ALL") {
+                    setFilters((prev) => ({
+                        ...prev,
+                        sggNm: null,
+                        sggSewerBzmnCd: "ALL",
+                        sewerBzmnCd:
+                            prev.ctpvSewerBzmnCd &&
+                            prev.ctpvSewerBzmnCd !== "ALL"
+                                ? prev.ctpvSewerBzmnCd
+                                : null,
+                    }));
+                } else {
+                    setFilters((prev) => ({
+                        ...prev,
+                        sewerBzmnCd: value,
+                        sggNm: optionData?.label,
+                        sggSewerBzmnCd: value,
+                    }));
+                }
                 return;
             }
 
@@ -588,23 +616,31 @@ function StatisticsVerificationReport() {
                 <div className="flex items-center gap-6">
                     <FilterSelect
                         label="시도"
-                        value={filters.ctpvSewerBzmnCd ?? ""}
+                        value={filters.ctpvSewerBzmnCd ?? "ALL"}
                         onChange={handleFilterChange("ctpvNm")}
-                        options={sidoList.map((item) => ({
-                            label: item.sido,
-                            value: item.bsnmCd,
-                        }))}
+                        options={[
+                            REGION_ALL_OPTION,
+                            ...sidoList.map((item) => ({
+                                label: item.sido,
+                                value: item.bsnmCd,
+                            })),
+                        ]}
                     />
                     <FilterSelect
                         label="시군구"
-                        value={filters.sggSewerBzmnCd ?? ""}
+                        value={filters.sggSewerBzmnCd ?? "ALL"}
                         onChange={handleFilterChange("sggNm")}
-                        options={
-                            sigunguData?.map((item) => ({
+                        disabled={
+                            !filters.ctpvSewerBzmnCd ||
+                            filters.ctpvSewerBzmnCd === "ALL"
+                        }
+                        options={[
+                            REGION_ALL_OPTION,
+                            ...(sigunguData?.map((item) => ({
                                 label: item.gugun,
                                 value: item.bsnmCd,
-                            })) ?? []
-                        }
+                            })) ?? []),
+                        ]}
                     />
                     <FilterSelect
                         label="년도"
@@ -752,6 +788,7 @@ interface FilterSelectProps {
     ) => void;
     options: Array<{ label: string; value: string }>;
     value?: string;
+    disabled?: boolean;
 }
 
 function FilterCombobox({
@@ -818,12 +855,19 @@ function FilterCombobox({
     );
 }
 
-function FilterSelect({ label, onChange, options, value }: FilterSelectProps) {
+function FilterSelect({
+    label,
+    onChange,
+    options,
+    value,
+    disabled,
+}: FilterSelectProps) {
     return (
         <div className="flex items-center gap-2">
             <Label className="whitespace-nowrap">{label}</Label>
             <Select
                 value={value}
+                disabled={disabled}
                 onValueChange={(value) =>
                     onChange(
                         value,
diff --git a/apps/st/src/components/statistics/verification/detail/HbVerificationDetail.tsx b/apps/st/src/components/statistics/verification/detail/HbVerificationDetail.tsx
index b8e5a3cd4..ed17b417b 100644
--- a/apps/st/src/components/statistics/verification/detail/HbVerificationDetail.tsx
+++ b/apps/st/src/components/statistics/verification/detail/HbVerificationDetail.tsx
@@ -40,8 +40,8 @@ const HbVerificationDetail: React.FC<HbVerificationDetailProps> = ({
     );
     const [checkedSns, setCheckedSns] = useState<string[]>([]);
     const [appliedFilter, setAppliedFilter] = useState<AppliedFilter>({
-        sido: "",
-        gugun: "",
+        sido: "ALL",
+        gugun: "ALL",
         status: "",
     });
     const [selectedRowId, setSelectedRowId] = useState<number | null>(null);
diff --git a/apps/st/src/components/statistics/verification/detail/RegionalGrid.tsx b/apps/st/src/components/statistics/verification/detail/RegionalGrid.tsx
index eeea43b3a..8eee4ec1a 100644
--- a/apps/st/src/components/statistics/verification/detail/RegionalGrid.tsx
+++ b/apps/st/src/components/statistics/verification/detail/RegionalGrid.tsx
@@ -26,6 +26,7 @@ import type { AppliedFilter } from "./HbVerificationDetail";
 import DataGrid from "@/components/module/DataGrid";
 
 const EMPTY_ADST_LIST: AdstZoneResponseDto[] = [];
+const REGION_ALL_VALUE = "ALL";
 
 interface RegionalGridProps {
     anlsSn: number;
@@ -53,7 +54,10 @@ const RegionalGrid: React.FC<RegionalGridProps> = ({
     >([]);
 
     const { data: sidoData } = useStAnlsSidoCombo();
-    const { data: gugunData } = useStAnlsSigunguCombo(appliedFilter.sido ?? "");
+    const sidoCd = appliedFilter.sido ?? "";
+    const { data: gugunData } = useStAnlsSigunguCombo(
+        sidoCd !== REGION_ALL_VALUE ? sidoCd : "",
+    );
     const sidoOptions = sidoData ?? EMPTY_ADST_LIST;
     const gugunOptions = gugunData ?? EMPTY_ADST_LIST;
 
@@ -66,14 +70,14 @@ const RegionalGrid: React.FC<RegionalGridProps> = ({
         let data = (resultData?.content ?? []) as StAnlsRsltResponse[];
         {
             const sidoCd = appliedFilter.sido;
-            if (sidoCd) {
+            if (sidoCd && sidoCd !== REGION_ALL_VALUE) {
                 data = data.filter((item) =>
                     item.admdstCd.startsWith(sidoCd.slice(0, 2)),
                 );
             }
 
             const gugunCd = appliedFilter.gugun;
-            if (gugunCd) {
+            if (gugunCd && gugunCd !== REGION_ALL_VALUE) {
                 data = data.filter((item) => item.admdstCd === gugunCd);
             }
 
@@ -107,13 +111,17 @@ const RegionalGrid: React.FC<RegionalGridProps> = ({
     }, [resultData, appliedFilter]);
 
     const handleSidoChange = (val: string) => {
-        onFilterChange({ ...appliedFilter, sido: val, gugun: "" });
+        onFilterChange({
+            ...appliedFilter,
+            sido: val,
+            gugun: REGION_ALL_VALUE,
+        });
     };
 
     const handleReset = () => {
         onFilterChange({
-            sido: "",
-            gugun: "",
+            sido: REGION_ALL_VALUE,
+            gugun: REGION_ALL_VALUE,
             status: "",
         });
     };
@@ -156,13 +164,16 @@ const RegionalGrid: React.FC<RegionalGridProps> = ({
             <div className="flex justify-between">
                 <div className="flex items-center gap-2">
                     <Select
-                        value={appliedFilter.sido || ""}
+                        value={appliedFilter.sido || REGION_ALL_VALUE}
                         onValueChange={handleSidoChange}
                     >
                         <SelectTrigger className="w-[12rem] bg-white">
-                            <SelectValue placeholder="시도 선택" />
+                            <SelectValue placeholder="전체" />
                         </SelectTrigger>
                         <SelectContent>
+                            <SelectItem value={REGION_ALL_VALUE}>
+                                전체
+                            </SelectItem>
                             {sidoOptions.map((opt) => (
                                 <SelectItem key={opt.adstCd} value={opt.adstCd}>
                                     {opt.adstNm}
@@ -171,16 +182,22 @@ const RegionalGrid: React.FC<RegionalGridProps> = ({
                         </SelectContent>
                     </Select>
                     <Select
-                        value={appliedFilter.gugun || ""}
+                        value={appliedFilter.gugun || REGION_ALL_VALUE}
                         onValueChange={(val) =>
                             onFilterChange({ ...appliedFilter, gugun: val })
                         }
-                        disabled={!appliedFilter.sido}
+                        disabled={
+                            !appliedFilter.sido ||
+                            appliedFilter.sido === REGION_ALL_VALUE
+                        }
                     >
                         <SelectTrigger className="w-[12rem] bg-white">
-                            <SelectValue placeholder="시군구 선택" />
+                            <SelectValue placeholder="전체" />
                         </SelectTrigger>
                         <SelectContent>
+                            <SelectItem value={REGION_ALL_VALUE}>
+                                전체
+                            </SelectItem>
                             {gugunOptions.map((opt) => (
                                 <SelectItem key={opt.adstCd} value={opt.adstCd}>
                                     {opt.adstNm}
diff --git a/apps/st/src/entities/statistics/api/queries.ts b/apps/st/src/entities/statistics/api/queries.ts
index b59af9f07..0553db787 100644
--- a/apps/st/src/entities/statistics/api/queries.ts
+++ b/apps/st/src/entities/statistics/api/queries.ts
@@ -73,7 +73,7 @@ export const useStAnlsSigunguCombo = (sidoCd: string) => {
     return useQuery({
         queryKey: [ENDPOINT.STATVERIFY_SERVICE.ST_ANLS_MST, "sigungu", sidoCd],
         queryFn: () => statisticsAnalysisMasterService.getSigunguCombo(sidoCd),
-        enabled: Boolean(sidoCd),
+        enabled: Boolean(sidoCd) && sidoCd !== "ALL",
     });
 };