The occurrence or non-occurrence of a certain slip of a drive wheel is detected based on only a motor torque used for driving a vehicle, a brake torque, and a rotation speed of a motor computed from an output of a rotational position detection sensor. In response to detection of the occurrence of the certain slip, drive restriction of the motor is activated for slip control. The slip control is attainable by a brake system and the drive restriction of the motor. Even in the event of any failure or abnormality arising in the brake system or in the event of prohibiting traction control of the brake system in response to the driver's operation of a TRC off switch, the drive restriction of the motor accomplishes the slip control. This arrangement desirably prevents slip-induced unstable driving of the vehicle and damages of devices involved in slip control for the vehicle.