diff --git a/README.md b/README.md
index bb32a053..0fdf1cce 100644
--- a/README.md
+++ b/README.md
@@ -105,3 +105,8 @@ We follow Rust best practices for testing:
 - **Integration tests** controlled by feature flags (opt-in when database is available)
 - **Cargo-native** test execution using standard `cargo test` commands
 - **Makefile shortcuts** for common testing workflows
+
+## Data Sources
+
+- Bus-related data provided by [Tokyo Metropolitan Bureau of Transportation (Toei)](https://www.kotsu.metro.tokyo.jp/), licensed under [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/)
+- Station data provided by [駅データ.jp](https://www.ekidata.jp/)