In a case where a manipulation switch is manipulated when a limit switch detects the fact that the seat back is in an upright position, an ECU controls driving of a motor until a sector gear turned in a second turning direction moves a lock lever in a lock release direction at a second abutting portion thereby to cause a lock member to be in a lock release state. Also, in a case where the manipulation switch is manipulated when the limit switch detects the fact that the seat back is not in the upright position, the ECU controls driving of the motor until the limit switch detects the fact that the seat back is in the upright position.