PURPOSE: To practically fix the position of a yawing center by giving a rear wheel steering operation to a rear wheel steering mechanism in order to make the side slipping speed found by a side slipping detecting means to zero at the time when a vehicle is in a traveling state accompanied by the change of its front wheel steering angle.

CONSTITUTION: A control unit 100 finds a transverse acceleration Yg in Go on the vehicle centroid based on the detection signal Sg fed from a transverse acceleration sensor 32, a yawangle speed W in the centroid Go based on the detection signal Sw fed from a yawangle speed sensor 34 and a vehicle traveling speed based on the detection signal Sv fed from a car speed sensor 36, and an aiming rear wheel steering angle Tor is calculated. The control unit 100 calculates the difference Δθ in the aiming rear wheel steering angle Tor and the rear wheel steering angle θr obtd. based on the detection signal Sr fed from a steering angle sensor 38 and fed to a driving circuit part 40. A rear wheel 14 is steered so that the rear wheel steering angle θr becomes equal to the aiming rear wheel steering angle Tor according to the signal fed from the driving circuit part.