To provide a necktie clasp simple in structure, not appearing on the surface of a necktie, and capable of locking the necktie at an arbitrary height regardless of the position of a button of a shirt.

This necktie clasp is provided with a plate-like insert plate 16 made of a synthetic resin, which is inserted inside a band piece 14 on the back of the necktie 12, a clip plate 28 rockably overlapping a part of the insert plate 16, and an elastic part 22 for energizing the clip plate 28 toward the insert plate 16. The end part of the clip plate 28 on the opposite side to the center of rocking is provided with a relief part 32 formed inside the clip plate 28. The insert plate 16 is made of a synthetic resin having elasticity and the elastic part 22 is integrally formed on the insert plate 16.