diff --git a/.github/copilot-instructions.md b/.github/copilot-instructions.md
new file mode 100644
index 0000000000..7c30489afe
--- /dev/null
+++ b/.github/copilot-instructions.md
@@ -0,0 +1,3 @@
+# Copilot Instructions for Misskey
+
+- en-US.yml を編集しないでください。