diff --git a/LICENSE b/LICENSE
new file mode 100644
index 0000000..ed85d76
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2026 Kei-Luna and Naruse
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
diff --git a/README.md b/README.md
index f6859e2..c74d40c 100644
--- a/README.md
+++ b/README.md
@@ -87,6 +87,9 @@ dotnet build
 - [Naruse](https://github.com/DevilProMT)
 - [Kei-Luna](https://github.com/Kei-Luna)
 
+## License
+This repository is licensed under the [MIT License](LICENSE).
+
 ## Notes on use
 This software is intended for research and testing purposes in a local environment.  
 It is not intended for unauthorized access to, interference with, or commercial use of official services.
diff --git a/README_jp.md b/README_jp.md
index e09734d..35c9d0b 100644
--- a/README_jp.md
+++ b/README_jp.md
@@ -87,6 +87,8 @@ dotnet build
 - [Naruse](https://github.com/DevilProMT)
 - [Kei-Luna](https://github.com/Kei-Luna)
 
+## ライセンス
+このリポジトリは [MIT License](LICENSE) の下で公開されています。
 
 ## 利用上の注意
 本ソフトウェアはローカル環境での研究・検証用途を想定しています。