diff --git a/.vitepress/config.mjs b/.vitepress/config.mjs
index cd9716ed..7a1d4eae 100644
--- a/.vitepress/config.mjs
+++ b/.vitepress/config.mjs
@@ -232,8 +232,17 @@ export default defineConfig({
             ],
           },
           {
-            text: "Markdown設計ドキュメント規約",
-            link: "/documents/forMarkdown/",
+            text: "Markdown",
+            items: [
+              {
+                text: "Introduction",
+                link: "/documents/forMarkdown/",
+              },
+              {
+                text: "Markdown設計ドキュメント規約",
+                link: "/documents/forMarkdown/markdown_design_document.html",
+              },
+            ],
           },
           {
             text: "Slack",