In response to detection of a slip occurring on left and right front wheels (62a, 62b) caused by spin of one of the left and right front wheels (62a, 62b), the control technique of the invention restricts a torque output from a motor (22)to a drive shaft (28), while activating a hydraulic brake (54a) or (54b) corresponding to the spinning wheel to output a brake torque, so as to distribute the output torque of the motor (22) practically equally into the left and right front wheels (62a, 62b). This arrangement desirably improves the starting performance and the accelerating performance of a vehicle with the left and right front wheels (62a, 62b) running on the road surface of different frictional coefficients.