diff --git a/src/middleware.ts b/src/middleware.ts
index 578b00a..bbee32a 100644
--- a/src/middleware.ts
+++ b/src/middleware.ts
@@ -1,6 +1,7 @@
 import { NextResponse, NextRequest } from "next/server";
 import { jwtDecode } from "jwt-decode";
 import { ROLE_AREAS } from "@/constants/ROLE_AREAS";
+import { getAuthCookieDomain } from "@/utils/getAuthCookieDomain/getAuthCookieDomain";
 
 interface JwtPayload {
   role?: string;
@@ -23,9 +24,10 @@ const getHomeByRole = (role: string | null) =>
 const findArea = (pathname: string) =>
   ROLE_AREAS.find((area) => pathname === area.home || pathname.startsWith(`${area.home}/`));
 
-const clearTokens = (response: NextResponse) => {
-  response.cookies.set("access_token", "", { path: "/", maxAge: 0 });
-  response.cookies.set("refresh_token", "", { path: "/", maxAge: 0 });
+const clearTokens = (request: NextRequest, response: NextResponse) => {
+  const domain = getAuthCookieDomain(request.headers.get("host"));
+  response.cookies.set("access_token", "", { path: "/", maxAge: 0, domain });
+  response.cookies.set("refresh_token", "", { path: "/", maxAge: 0, domain });
   return response;
 };
 
@@ -44,16 +46,17 @@ export function middleware(request: NextRequest) {
     return NextResponse.redirect(loginUrl);
   };
 
-  // 권한이 없는 계정으로 로그인하면 토큰을 지우고 로그인 화면에 안내를 띄운다.
+  // 권한이 없는 계정이면 로그인 화면에 안내만 띄운다.
+  // 토큰은 운영 앱과 공유하므로 여기서 지우면 운영 앱 세션까지 끊긴다.
   const redirectForbidden = () => {
     const loginUrl = new URL(LOGIN_PATH, request.url);
     loginUrl.searchParams.set("reason", "forbidden");
-    return clearTokens(NextResponse.redirect(loginUrl));
+    return NextResponse.redirect(loginUrl);
   };
 
   if (pathname.startsWith(LOGIN_PATH)) {
     const reason = request.nextUrl.searchParams.get("reason");
-    if (reason === "session-expired") return clearTokens(NextResponse.next());
+    if (reason === "session-expired") return clearTokens(request, NextResponse.next());
     if (reason !== "forbidden" && accessToken && hasRefreshToken && home) return redirectTo(home);
     return NextResponse.next();
   }
diff --git a/src/utils/getAuthCookieDomain/getAuthCookieDomain.ts b/src/utils/getAuthCookieDomain/getAuthCookieDomain.ts
new file mode 100644
index 0000000..4eb24da
--- /dev/null
+++ b/src/utils/getAuthCookieDomain/getAuthCookieDomain.ts
@@ -0,0 +1,25 @@
+const AUTH_COOKIE_PARENT_DOMAIN = "finditem.kr";
+
+/**
+ * 토큰 쿠키를 지울 때 붙일 `domain` 값을 접속 호스트로 판정합니다.
+ *
+ * @remarks
+ * - 백엔드가 finditem.kr 계열 요청에는 토큰 쿠키를 상위 도메인으로 발급하므로, 지울 때도 같은 도메인을 줘야 지워집니다.
+ * - dev 서버는 middleware의 `nextUrl`을 자기 주소로 만들기 때문에 `Host` 헤더를 넘겨 판정합니다.
+ *
+ * @param host - 요청의 `Host` 헤더 값 (포트 포함 가능)
+ * @returns finditem.kr 또는 그 하위 도메인이면 `".finditem.kr"`, 아니면 `undefined`
+ *
+ * @example
+ * ```ts
+ * getAuthCookieDomain("a.finditem.kr"); // ".finditem.kr"
+ * getAuthCookieDomain("localhost:3000"); // undefined
+ * ```
+ */
+export const getAuthCookieDomain = (host: string | null) => {
+  const hostname = host?.split(":")[0] ?? "";
+  return hostname === AUTH_COOKIE_PARENT_DOMAIN ||
+    hostname.endsWith(`.${AUTH_COOKIE_PARENT_DOMAIN}`)
+    ? `.${AUTH_COOKIE_PARENT_DOMAIN}`
+    : undefined;
+};
diff --git a/src/utils/index.ts b/src/utils/index.ts
index 8b5e27a..2b7f453 100644
--- a/src/utils/index.ts
+++ b/src/utils/index.ts
@@ -14,3 +14,4 @@ export { applyFiltersToUrl } from "./applyFiltersToUrl/applyFiltersToUrl";
 export { getCategoryLabel } from "./getCategoryLabel/getCategoryLabel";
 export { getServiceUrl } from "./getServiceUrl/getServiceUrl";
 export { isValidCallbackUrl } from "./isValidCallbackUrl/isValidCallbackUrl";
+export { getAuthCookieDomain } from "./getAuthCookieDomain/getAuthCookieDomain";