A seat recliner for a vehicle is provided and includes: a first plate; a second plate coupled with the first plate to define an inner space; a locking gear provided in the inner space, and provided with external teeth engaged with the first plate or the second plate; a locking cam configured to move the locking gear; an input member configured such that a first end thereof passes through the first plate and is coupled with a center of a locking cam to transmit torque thereto, and a second end thereof is exposed outside the first plate; and an elastic member wound around an outer circumferential surface of the second end of the input member, and configured such that a first end thereof is stopped by the input member, and a second end is stopped by an outer side of the first plate, thereby providing a restoring force.