diff --git a/app/MetadataResolver/CienResolver.php b/app/MetadataResolver/CienResolver.php
index 47d0e44..9931ac4 100644
--- a/app/MetadataResolver/CienResolver.php
+++ b/app/MetadataResolver/CienResolver.php
@@ -27,18 +27,17 @@ class CienResolver extends MetadataResolver
         $res = $this->client->get($url);
         $metadata = $this->ogpResolver->parse((string) $res->getBody());
 
-        // 画像URLのJWTから有効期限を拾う
+        // JWTがついていれば画像URLのJWTから有効期限を拾う
         parse_str(parse_url($metadata->image, PHP_URL_QUERY), $params);
-        if (empty($params['jwt'])) {
-            throw new \RuntimeException('Parameter "jwt" not found. Image=' . $metadata->image . ' Source=' . $url);
-        }
-        $parts = explode('.', $params['jwt']);
-        if (count($parts) !== 3) {
-            throw new \RuntimeException('Invalid jwt. Image=' . $metadata->image . ' Source=' . $url);
-        }
-        $payload = json_decode(base64_decode(str_replace(['-', '_'], ['+', '/'], $parts[1])), true);
+        if (isset($params['jwt'])) {
+            $parts = explode('.', $params['jwt']);
+            if (count($parts) !== 3) {
+                throw new \RuntimeException('Invalid jwt. Image=' . $metadata->image . ' Source=' . $url);
+            }
+            $payload = json_decode(base64_decode(str_replace(['-', '_'], ['+', '/'], $parts[1])), true);
 
-        $metadata->expires_at = Carbon::createFromTimestamp($payload['exp']);
+            $metadata->expires_at = Carbon::createFromTimestamp($payload['exp']);
+        }
 
         return $metadata;
     }