diff --git a/apps/cm/app/api/proxy/[...url]/route.ts b/apps/cm/app/api/proxy/[...url]/route.ts
index 761991e39..ca15a1447 100644
--- a/apps/cm/app/api/proxy/[...url]/route.ts
+++ b/apps/cm/app/api/proxy/[...url]/route.ts
@@ -101,11 +101,19 @@ async function handler(
         [AUTH_USER_ID]: userId,
         ...responseData, // 2FA 관련 추가 데이터 포함
       });
+      const hostname = window.location.hostname;
+      let domain = hostname === "localhost" || hostname === "127.0.0.1" ? undefined : hostname;
+      
+      // 운영 환경에서는 서브도메인을 포함한 최상위 도메인 사용
+      if (hostname.includes("hasuon.or.kr")) {
+         domain = ".hasuon.or.kr";
+      }
 
       if (refreshToken) {
         cookieStore.set(REFRESH_TOKEN, refreshToken, {
           httpOnly: true,
           sameSite: "lax",
+          domain: domain,
           path: "/",
         });
       }
diff --git a/apps/cs/app/api/proxy/[...url]/route.ts b/apps/cs/app/api/proxy/[...url]/route.ts
index d3092c5c1..07fa4376f 100644
--- a/apps/cs/app/api/proxy/[...url]/route.ts
+++ b/apps/cs/app/api/proxy/[...url]/route.ts
@@ -60,10 +60,20 @@ async function handler(
         [AUTH_USER_ID]: userId,
       });
 
+      
+      const hostname = window.location.hostname;
+      let domain = hostname === "localhost" || hostname === "127.0.0.1" ? undefined : hostname;
+      
+      // 운영 환경에서는 서브도메인을 포함한 최상위 도메인 사용
+      if (hostname.includes("hasuon.or.kr")) {
+         domain = ".hasuon.or.kr";
+      }
+
       if (refreshToken) {
         cookieStore.set(REFRESH_TOKEN, refreshToken, {
           httpOnly: true,
           sameSite: "lax",
+          domain: domain,
           path: "/",
         });
       }
@@ -83,6 +93,7 @@ async function handler(
   }
 }
 
+
 export async function POST(
   request: Request,
   props: { params: Promise<{ url: string[] }> },