diff --git a/index.d.ts b/index.d.ts
new file mode 100644
index 0000000..15c2235
--- /dev/null
+++ b/index.d.ts
@@ -0,0 +1,12 @@
+import _josa from "josa"
+
+export type JosaFormat = '을/를' | '을' | '를' | '을를' | '은/는' | '은' | '는' | '은는' | '이/가' | '이' | '가' | '이가';
+
+export interface IJosa {
+  r: (word: string, format: JosaFormat) => string,
+  c: (word: string, format: JosaFormat) => string
+}
+
+declare const Josa: IJosa = _josa;
+
+export default Josa
\ No newline at end of file