diff --git a/404.html b/404.html
index 452e92d6..7a18e1c0 100644
--- a/404.html
+++ b/404.html
@@ -33,7 +33,21 @@ <h1>404</h1>
   <div><img src="/assets/img/spinner.svg" data-src="/assets/img/404.webp" alt="404 Page Not Found" width="200px" style="margin-top: -50px;" class="lazyload" /></div>
   <span>リンク切れの場合は <a href="https://twitter.com/MitouJr">@MitouJr</a> までご連絡して頂けると嬉しいです。</span>
 
-  <p><a href="javascript:history.back()">« 戻る</a></p>
+  <script type="text/javascript">
+   function historyBackOrDefault() {
+     console.log(history.length);
+      if (history.back() === undefined ) {
+	if (window.location.href.indexOf("/english") != -1) {
+	  window.location.replace("/english");
+        } else {
+ 	  window.location.replace("/");
+	}
+      } else {
+	history.back();
+      }
+    }
+  </script>
+  <p><a href="javascript:historyBackOrDefault()">« 戻る</a></p>
 
   <div style='margin-top: 100px;'>
     <a class="twitter-timeline" data-lang="ja" data-height="700"
diff --git a/english/404.html b/english/404.html
index 911fcec6..bf03dd9e 100644
--- a/english/404.html
+++ b/english/404.html
@@ -33,7 +33,22 @@ <h1>404</h1>
   <div><img src="/assets/img/spinner.svg" data-src="/assets/img/404_en.webp" alt="404 Page Not Found" width="200px" style="margin-top: -50px;" class="lazyload" /></div>
   <span>Contact <a href="https://twitter.com/MitouJr">@MitouJr</a> if this is an erorr to report.</span>
 
-  <p><a href="javascript:history.back()">« Back</a></p>
+  <script type="text/javascript">
+   function historyBackOrDefault() {
+     console.log(history.length);
+      if (history.back() === undefined ) {
+	if (window.location.href.indexOf("/english") != -1) {
+	  window.location.replace("/english");
+        } else {
+ 	  window.location.replace("/");
+	}
+      } else {
+	history.back();
+      }
+    }
+  </script>
+
+  <p><a href="javascript:historyBackOrDefault()">« Back</a></p>
 
   <div style='margin-top: 100px;'>
     <a class="twitter-timeline" data-lang="en" data-height="700"