The disclosure reduces inconvenience for a driver at the time of operating parking locking, thereby curbing cost reduction and space saving becoming difficult due to additional installation of a drive source for parking locking. The disclosure provides a motor driver mounted on a vehicle, including a rotation prevention arm which can move between a position where it is interposed between teeth of a parking gear portion to prevent rotation of a second gear thereby preventing rotation of each gear in a transaxle and a position where it is not interposed between the teeth, and a transmission mechanism which transmits a driving force of a motor shaft of an electric pump for transferring oil in a housing of the transaxle to the rotation prevention arm.