diff --git a/.github/scripts/release.js b/.github/scripts/release.js
new file mode 100644
index 0000000..287f80b
--- /dev/null
+++ b/.github/scripts/release.js
@@ -0,0 +1,28 @@
+const path = require("path");
+const fs = require("fs").promises;
+const crypto = require("crypto");
+
+/** actions/github-script でのリリース成果物のアップロード */
+module.exports = async function ({ github, context, glob }) {
+  const version = context.payload.release.tag_name.replace(/^v/i, "");
+  const target = {
+    ...context.repo,
+    release_id: context.payload.release.id,
+  };
+  let body = "## Megabit OS\n";
+  const globber = await glob.create("megabit-armhf.*.gz");
+  for await (const file of globber.globGenerator()) {
+    const name = path
+      .basename(file)
+      .replace(/^megabit-armhf[.]/, `megabit-${version}-armhf.`);
+    const data = await fs.readFile(file);
+    await github.repos.uploadReleaseAsset({ ...target, name, data });
+    const hash = crypto.createHash("sha256").update(data).digest("hex");
+    body = `${body}
+${name.split(".").includes("img") ? "OS イメージ" : "ファイルシステム"}
+
+- ${name} (SHA256: \`${hash}\`)
+`;
+  }
+  await github.repos.updateRelease({ ...target, body, prerelease: false });
+};
diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index d667a4d..7ddaa85 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -1,6 +1,8 @@
 name: build
 on:
   push: { branches: [main] }
+  release:
+    types: [published]
 jobs:
   main:
     runs-on: ubuntu-latest
@@ -14,3 +16,16 @@ jobs:
         with:
           name: megabit-armhf
           path: megabit-armhf.*
+  release:
+    if: github.event.release.prerelease
+    needs: main
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions/download-artifact@v2
+        with: { name: megabit-armhf }
+      - uses: actions/github-script@v4
+        with:
+          script: |
+            const script = require("./.github/scripts/release.js");
+            await script({ github, context, glob });