diff --git a/API.md b/API.md
index c906ba5..d0bd646 100644
--- a/API.md
+++ b/API.md
@@ -1,6 +1,18 @@
# API Reference
+## Structs
+
+### Naming
+
+#### Initializer
+
+```typescript
+import { ResourceNaming } from '@gammarers/aws-resource-naming'
+
+const naming: ResourceNaming.Naming = { ... }
+```
+