diff --git a/app/[...slug]/opengraph-image.tsx b/app/[...slug]/opengraph-image.tsx
new file mode 100644
index 00000000..15335d2b
--- /dev/null
+++ b/app/[...slug]/opengraph-image.tsx
@@ -0,0 +1,107 @@
+import { ImageResponse } from "next/og"
+import { getPostByPath, getAllPosts } from "@/lib/posts"
+
+export const contentType = "image/png"
+export const size = { width: 1200, height: 630 }
+
+export async function generateStaticParams() {
+  const posts = await getAllPosts()
+  return posts.map((post) => ({
+    slug: post.path.replace(/^\//, "").split("/"),
+  }))
+}
+
+// Google Fonts から Noto Sans JP を読み込む
+async function loadGoogleFont(text: string): Promise<ArrayBuffer | null> {
+  try {
+    const url = `https://fonts.googleapis.com/css2?family=Noto+Sans+JP:wght@700&text=${encodeURIComponent(text)}`
+    const css = await (await fetch(url)).text()
+    const match = css.match(/src: url\((.+?)\) format\('woff2'\)/)
+    if (!match) return null
+    return fetch(match[1]).then((res) => res.arrayBuffer())
+  } catch {
+    return null
+  }
+}
+
+export default async function OGImage({
+  params,
+}: {
+  params: Promise<{ slug: string[] }>
+}) {
+  const { slug } = await params
+  const postPath = "/" + slug.join("/")
+  const post = await getPostByPath(postPath)
+
+  const title = post?.title || "jaxx2104.info"
+
+  // タイトルに含まれる文字 + サイト名の文字でフォントを読み込む
+  const fontData = await loadGoogleFont(title + "jaxx2104.info")
+
+  return new ImageResponse(
+    (
+      <div
+        style={{
+          width: "100%",
+          height: "100%",
+          display: "flex",
+          flexDirection: "column",
+          justifyContent: "center",
+          alignItems: "center",
+          background: "linear-gradient(135deg, #667eea 0%, #764ba2 100%)",
+          padding: "60px",
+        }}
+      >
+        <div
+          style={{
+            display: "flex",
+            flexDirection: "column",
+            justifyContent: "center",
+            alignItems: "center",
+            background: "white",
+            borderRadius: "20px",
+            width: "100%",
+            height: "100%",
+            padding: "40px 60px",
+          }}
+        >
+          <div
+            style={{
+              fontSize: title.length > 30 ? 48 : 56,
+              fontWeight: 700,
+              color: "#1a1a1a",
+              textAlign: "center",
+              lineHeight: 1.4,
+              maxWidth: "100%",
+              wordBreak: "break-word",
+            }}
+          >
+            {title}
+          </div>
+          <div
+            style={{
+              marginTop: "auto",
+              fontSize: 28,
+              color: "#666",
+            }}
+          >
+            jaxx2104.info
+          </div>
+        </div>
+      </div>
+    ),
+    {
+      ...size,
+      ...(fontData && {
+        fonts: [
+          {
+            name: "Noto Sans JP",
+            data: fontData,
+            style: "normal" as const,
+            weight: 700 as const,
+          },
+        ],
+      }),
+    }
+  )
+}
diff --git a/app/[...slug]/page.tsx b/app/[...slug]/page.tsx
index d298e7db..ed339fa5 100644
--- a/app/[...slug]/page.tsx
+++ b/app/[...slug]/page.tsx
@@ -34,7 +34,6 @@ export async function generateMetadata({
   const title = `${post.title} | jaxx2104.info`
   const description = post.content?.split(/\n/)[0] || ""
   const url = `${siteUrl}${post.path}`
-  const imageUrl = post.thumbnail ? `${siteUrl}${post.thumbnail}` : undefined
 
   return {
     title,
@@ -45,17 +44,11 @@ export async function generateMetadata({
       url,
       siteName: "jaxx2104.info",
       type: "article",
-      ...(imageUrl && {
-        images: [{ url: imageUrl }],
-      }),
     },
     twitter: {
-      card: imageUrl ? "summary_large_image" : "summary",
+      card: "summary_large_image",
       title,
       description,
-      ...(imageUrl && {
-        images: [imageUrl],
-      }),
     },
   }
 }