PURPOSE: To make the improvement of transient performance at the time of normal input compatible with the improvement of disturbance resistance at the time of reverse input by providing a front wheel steering system input direction discriminating means, a rear wheel steering angle control means for normal input and a rear wheel steering angle control means for reverse input.

CONSTITUTION: In steering rear wheels at the time of steering front wheels, a front wheel steering system input direction discriminating means first discriminates whether the input to the front wheel steering system is the normal input from the steering wheel side or the reverse input from the front wheel side. According to this discriminated result, if the input is normal, a rear wheel steering angle control means for normal input determines a rear wheel steering angle corresponding to the front wheel steering angle, and if the input is reverse, a rear wheel steering angle control means for reverse input determines a rear wheel steering angle corresponding to the front wheel control force; and the rear wheels are steered by this determined steering angle. The improvement of transient performance required at the time of normal input and disturbance resistance required at the time of reverse input can be made compatible by steering the wheels according to the front wheel steering angle at the time normal input and according to the front wheel control force at the of reverse input.