diff --git a/_config.yml b/_config.yml
index 368503d..cf3ce51 100644
--- a/_config.yml
+++ b/_config.yml
@@ -26,8 +26,8 @@ navbar:
     menu:
         # Home: /
         Archives: /archives
-        サークル参加😺: https://techbookfest.org/event/tbf13#requirements
-        技術書典13（オンライン：9/10-9/25、オフライン：9/11）: https://techbookfest.org/event/tbf13
+        サークル参加😺: https://techbookfest.org/event/tbf14#requirements
+        技術書典14（オンライン：5/20-6/4、オフライン：5/21）: https://techbookfest.org/event/tbf14
         # Categories: /categories
         # Tags: /tags
         # About: /about
diff --git a/includes/helpers/page.js b/includes/helpers/page.js
index a44c37b..b755e28 100644
--- a/includes/helpers/page.js
+++ b/includes/helpers/page.js
@@ -115,7 +115,7 @@ module.exports = function (hexo) {
         else if (hasThumbnail)
             og_image = getThumbnail(post);
         else
-            og_image = getConfig('article.og_image', '/images/og_image.png');
+            og_image = getConfig('article.og_image', '/images/og_image.jpg');
 
         return this.url_for(og_image);
     });
diff --git a/source/images/og_image.jpg b/source/images/og_image.jpg
new file mode 100644
index 0000000..6ce8d38
Binary files /dev/null and b/source/images/og_image.jpg differ
diff --git a/source/images/og_image.png b/source/images/og_image.png
deleted file mode 100644
index 723ff33..0000000
Binary files a/source/images/og_image.png and /dev/null differ