diff --git a/.github/workflows/manifest.yml b/.github/workflows/manifest.yml
index c5a410d3..5c74fbe1 100644
--- a/.github/workflows/manifest.yml
+++ b/.github/workflows/manifest.yml
@@ -52,7 +52,7 @@ jobs:
       - name: Handle diff
         id: diff
         run: tools/ci/manifest.sh
-        if: github.repository_owner == 'taiki-e' && (github.event_name == 'schedule' || github.event_name == 'push' && github.ref == 'refs/heads/main')
+        if: github.repository_owner == 'taiki-e' && (github.event_name == 'schedule' || github.event_name == 'workflow_dispatch' || github.event_name == 'push' && github.ref == 'refs/heads/main')
       - run: git add -N . && git -c color.ui=always diff --exit-code
       - id: create-pull-request
         uses: peter-evans/create-pull-request@v7
@@ -64,16 +64,16 @@ jobs:
             This will be auto-merged when CI has passed because this is an auto-generated PR in a defined format and is usually considered no additional review is required.
           branch: update-manifest
           token: ${{ secrets.CREATE_PR_TOKEN }}
-        if: github.repository_owner == 'taiki-e' && (github.event_name == 'schedule' || github.event_name == 'push' && github.ref == 'refs/heads/main') && steps.diff.outputs.success == 'false'
+        if: github.repository_owner == 'taiki-e' && (github.event_name == 'schedule' || github.event_name == 'workflow_dispatch' || github.event_name == 'push' && github.ref == 'refs/heads/main') && steps.diff.outputs.success == 'false'
       - name: Enable auto-merge for auto-generated PR
         run: gh pr merge --rebase --auto "${PR_NUMBER:?}"
         env:
           GITHUB_TOKEN: ${{ secrets.CREATE_PR_TOKEN }}
           PR_NUMBER: ${{ steps.create-pull-request.outputs.pull-request-number }}
-        if: github.repository_owner == 'taiki-e' && (github.event_name == 'schedule' || github.event_name == 'push' && github.ref == 'refs/heads/main') && steps.diff.outputs.success == 'false' && steps.create-pull-request.outputs.pull-request-operation == 'created'
+        if: github.repository_owner == 'taiki-e' && (github.event_name == 'schedule' || github.event_name == 'workflow_dispatch' || github.event_name == 'push' && github.ref == 'refs/heads/main') && steps.diff.outputs.success == 'false' && steps.create-pull-request.outputs.pull-request-operation == 'created'
       - name: Approve auto-generated PR for auto-merge
         run: gh pr review --approve "${PR_NUMBER:?}"
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
           PR_NUMBER: ${{ steps.create-pull-request.outputs.pull-request-number }}
-        if: github.repository_owner == 'taiki-e' && (github.event_name == 'schedule' || github.event_name == 'push' && github.ref == 'refs/heads/main') && steps.diff.outputs.success == 'false' && (steps.create-pull-request.outputs.pull-request-operation == 'created' || steps.create-pull-request.outputs.pull-request-operation == 'updated')
+        if: github.repository_owner == 'taiki-e' && (github.event_name == 'schedule' || github.event_name == 'workflow_dispatch' || github.event_name == 'push' && github.ref == 'refs/heads/main') && steps.diff.outputs.success == 'false' && (steps.create-pull-request.outputs.pull-request-operation == 'created' || steps.create-pull-request.outputs.pull-request-operation == 'updated')