diff --git a/TODO.md b/TODO.md
index 7b283bd..5813842 100644
--- a/TODO.md
+++ b/TODO.md
@@ -12,4 +12,4 @@
 - [x] equalsの一般化
 - [ ] timesの一般化
 - [x] FrancとDollarの比較
-- [ ] 通貨の概念
+- [x] 通貨の概念
diff --git a/src/__tests__/money.test.ts b/src/__tests__/money.test.ts
index 7c4131b..b775c64 100644
--- a/src/__tests__/money.test.ts
+++ b/src/__tests__/money.test.ts
@@ -3,21 +3,24 @@
 import { Money, Dollar, Franc } from '../money';
 
 test('equals', () => {
-  expect(new Franc(5).equals(new Franc(5))).toBeTruthy();
-  expect(new Franc(5).equals(new Franc(6))).toBeFalsy();
-  expect(new Dollar(5).equals(new Dollar(5))).toBeTruthy();
-  expect(new Dollar(5).equals(new Dollar(6))).toBeFalsy();
+  expect(Money.franc(5).equals(Money.franc(5))).toBeTruthy();
+  expect(Money.franc(5).equals(Money.franc(6))).toBeFalsy();
+  expect(Money.dollar(5).equals(Money.dollar(5))).toBeTruthy();
+  expect(Money.dollar(5).equals(Money.dollar(6))).toBeFalsy();
 });
 
 test('null equals', () => {
-  const francFive = new Franc(5);
+  const francFive = Money.franc(5);
   expect(francFive.equals(null)).toBeFalsy();
 
-  const dollarFive = new Dollar(6);
+  const dollarFive = Money.dollar(6);
   expect(dollarFive.equals(null)).toBeFalsy();
 });
 
 test('equals Franc = Dollar', () => {
+  expect(Money.franc(5).equals(Money.dollar(5))).toBeTruthy();
+  expect(Money.franc(5).equals(Money.dollar(6))).toBeFalsy();
+});
 
 test('currency', () => {
   expect(Money.dollar(1).currency).toBe('USD');