In a vehicle including a VGRS actuator capable of changing the steering transmission ratio by rotating an upper steering shaft and a lower steering shaft relative to each other, an ECU performs a lock releasing process when the VGRS motor is locked. In the process, an actual steering angle is calculated, and is compared with a lock release threshold value that is set in advance in view of the axial force applied to the lower steering shaft during steering. If the actual steering angle is equal to or smaller than the lock release threshold value, the ECU performs driving control of a lock mechanism so as to release the locked state of the VGRS motor.