diff --git a/apps/cs/src/pages/site/ui/modify-page.tsx b/apps/cs/src/pages/site/ui/modify-page.tsx
index 39d69f9e7..4f0924a07 100644
--- a/apps/cs/src/pages/site/ui/modify-page.tsx
+++ b/apps/cs/src/pages/site/ui/modify-page.tsx
@@ -29,7 +29,7 @@ function ModifyPage({ siteId }: { siteId: string }) {
   });
 
   useEffect(() => {
-    if (siteDetail === undefined && siteId) {
+    if (siteDetail === null && siteId) {
       alert("사이트 정보를 찾을 수 없습니다.", () => router.push("/site"));
     }
   }, [siteDetail, siteId]);