A control device applied to a vehicle equipped with: an electric motor having a rotary shaft linked to the drive wheels of the vehicle; a rotational position detector that detects the rotational position of the rotary shaft of the electric motor; and a battery. The control device executes an offset amount acquisition process, which is a process for obtaining an offset amount in response to a request for this offset amount, which is the difference between the rotational position of the rotary shaft as detected by the rotational position detector and the actual rotational position of the rotary shaft. In addition, the control device stores the obtained offset amount, and maintains that stored offset amount without relying on the power supplied form the battery. The control device is constructed so as to determine that a request to obtain an offset amount has been generated when the battery is separated from the vehicle.