A control device is applied to a vehicle having a motor with a rotary shaft connected to a drive shaft of the vehicle, a rotational position detector to detect a rotational position of the rotary shaft of the motor, and a battery. The control device performs a procedure for obtaining an offset amount in response to a request for obtaining the offset amount, store the obtained offset amount, and keep the stored offset amount without relying on electric power supplied from the battery, which offset amount is a difference between a detected rotational position of the rotary shaft with the rotational position detector and an actual rotational position of the rotary shaft. The control device is configured to find an occurrence of the request for obtaining the offset amount when battery is dismounted from the vehicle.