diff --git a/api/.htaccess b/api/.htaccess
index 40e8812..68ad3cd 100644
--- a/api/.htaccess
+++ b/api/.htaccess
@@ -1,8 +1,8 @@
-# --- APIはそのまま返す ---
+# --- エラーハンドリング(API) ---
 ErrorDocument 400 ""
 ErrorDocument 401 ""
 ErrorDocument 403 ""
-ErrorDocument 404 ""
+ErrorDocument 404 /errorpage/notfound.json
 ErrorDocument 413 ""
 ErrorDocument 500 ""
 ErrorDocument 502 ""
diff --git a/api/me/settings/index.php b/api/me/settings/index.php
index c4c6540..d1f79a5 100644
--- a/api/me/settings/index.php
+++ b/api/me/settings/index.php
@@ -84,7 +84,7 @@ if (isset($_GET['token']) || (!(empty($Get_Post_Json)))) {
                     // 文字数を確認
                     if (50 < mb_strlen($username, 'UTF-8')) {
                         $error_message[] = 'ユーザーネームは50文字以内で入力してください。(USERNAME_OVER_MAX_COUNT)';
-                        http_response_code(400);
+                        http_response_code(413);
                     }
                 }
 
diff --git a/api/users/follow.php b/api/users/follow.php
index e369912..7396f10 100644
--- a/api/users/follow.php
+++ b/api/users/follow.php
@@ -111,7 +111,7 @@ if(isset($_GET['token']) || (!(empty($Get_Post_Json)))) {
                         'error_code' => $err,
                         'success' => false
                     );
-                    http_response_code(400);
+                    http_response_code(500);
                     echo json_encode($response, JSON_UNESCAPED_UNICODE);
                 }
             }else{
diff --git a/errorpage/notfound.json b/errorpage/notfound.json
new file mode 100644
index 0000000..c577226
--- /dev/null
+++ b/errorpage/notfound.json
@@ -0,0 +1,4 @@
+{
+  "success": false,
+  "error_code": "endpoint_notfound"
+}
diff --git a/settings_admin/maintenance_admin.php b/settings_admin/maintenance_admin.php
index 9901130..334c90e 100644
--- a/settings_admin/maintenance_admin.php
+++ b/settings_admin/maintenance_admin.php
@@ -151,6 +151,7 @@ RewriteRule ^.*$ /errorpage/serverstop.json [R=500,L]
 ErrorDocument 403 /errorpage/serverstop.php
 RewriteCond %{REQUEST_URI} !=/function/function.php
 RewriteCond %{REQUEST_URI} !=/errorpage/serverstop.php
+RewriteCond %{REQUEST_URI} !=/errorpage/serverstop.json
 RewriteCond %{REQUEST_URI} !=/css/home.css
 RewriteCond %{REQUEST_URI} !=/css/color.css
 RewriteCond %{REQUEST_URI} !=/js/console_notice.js