diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2fd8301d..751378fe 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,8 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 
 ## [Unreleased]
 
+## [3.1.1] - 2024-03-21
+
 ### Changed
 - Update dependencies in [#281](https://github.com/cybozu-go/sabakan/pull/281)
 
@@ -322,7 +324,8 @@ No changes.  Only for updating Docker base image.
 
 See [CHANGELOG-0](./CHANGELOG-0.md).
 
-[Unreleased]: https://github.com/cybozu-go/sabakan/compare/v3.1.0...HEAD
+[Unreleased]: https://github.com/cybozu-go/sabakan/compare/v3.1.1...HEAD
+[3.1.1]: https://github.com/cybozu-go/sabakan/compare/v3.1.0...v3.1.1
 [3.1.0]: https://github.com/cybozu-go/sabakan/compare/v3.0.0...v3.1.0
 [3.0.0]: https://github.com/cybozu-go/sabakan/compare/v2.13.2...v3.0.0
 [2.13.2]: https://github.com/cybozu-go/sabakan/compare/v2.13.1...v2.13.2
diff --git a/version.go b/version.go
index 138555af..b90e33c5 100644
--- a/version.go
+++ b/version.go
@@ -1,7 +1,7 @@
 package sabakan
 
 // Version is sabakan version
-const Version = "3.1.0"
+const Version = "3.1.1"
 
 // SchemaVersion is the schema version
 const SchemaVersion = "3"