diff --git a/src/Site/Controller/User.php b/src/Site/Controller/User.php
index 6e6246d..3b4c645 100644
--- a/src/Site/Controller/User.php
+++ b/src/Site/Controller/User.php
@@ -158,6 +158,10 @@ class User {
       $auth = new Auth;
       $user = $auth->getLoggedInUser();
       $u = $auth->getUser($name);
+      if (!$u) {
+        header('Location: /404');
+        exit();
+      }
 
       $tmpl = new Template('/');
       $pagetit = 'サインイン';
diff --git a/src/Site/Lib/Auth.php b/src/Site/Lib/Auth.php
index 04ab889..61ee4f1 100644
--- a/src/Site/Lib/Auth.php
+++ b/src/Site/Lib/Auth.php
@@ -34,8 +34,9 @@ class Auth {
     return $this->pubUser;
   }
 
-  public function getUser(string $name): \stdClass {
+  public function getUser(string $name): \stdClass|null {
     $user = $this->getUserDataFromName($name);
+    if (!$user) return null;
     unset($user->password);
     unset($user->tokens);
     $myself = $this->getUserData();
@@ -306,7 +307,7 @@ class Auth {
     return json_decode($lines);
   }
 
-  private function getUserDataFromName(string $name): \stdClass {
+  private function getUserDataFromName(string $name): \stdClass|null {
     if (!AUTH_ENABLED) return new \stdClass;
     $file = scandir($this->dataDir);
     $userFile = "";
@@ -321,6 +322,7 @@ class Auth {
         }
       }
     }
+    if (!$userFile) return null;
     $path = $this->dataDir.$userFile;
     unset($file, $userFile);