diff --git a/src/pages/admin/signups/[id].tsx b/src/pages/admin/signups/[id].tsx
index 16cafb0..62aa0d7 100644
--- a/src/pages/admin/signups/[id].tsx
+++ b/src/pages/admin/signups/[id].tsx
@@ -110,7 +110,7 @@ const SignupCreatePage: NextPage = () => {
 
   useEffect(() => {
     const suId = id && Number(id);
-    if (suId !== undefined) {
+    if (suId !== undefined && !Number.isNaN(suId)) {
       SignupApi.getForm(suId, true)
         .then((res) => {
           setFormData({