A drive power distribution control section calculates an engaging torque
of clutch means including an input torque sensitive transfer torque, a
steering angle/yaw rate sensitive transfer torque, and a tack-in
prevention transfer torque. The input torque sensitive transfer torque is
estimated by using respective time constants corresponding to an
increasing or decreasing of the engine torque. Also, when the input
torque is large, a variation of the input torque sensitive transfer
torque is increased. The steering angle/yaw rate sensitive transfer
torque is corrected by an yaw moment according to an vehicle slip angular
velocity, and an upper limit is set on the variation of the yaw moment
per time.