diff --git a/src/pages/admin/SignupCreatePage.tsx b/src/pages/admin/SignupCreatePage.tsx
index 3a19dca..fb12661 100644
--- a/src/pages/admin/SignupCreatePage.tsx
+++ b/src/pages/admin/SignupCreatePage.tsx
@@ -138,6 +138,7 @@ class SignupCreatePage extends React.Component<SignupCreatePageProps, SignupCrea
         quota: {
           type: "integer",
           title: "Quota",
+          minimum: 0,
           default: null,
         },
         start_time: {