PURPOSE: To effectively work both rear wheel steering and toe-in control in a vehicle having operable rear wheels and variable toe-in by providing such a constitution as to control the toe-in to reduce tow-in at a predetermined speed or more, a predetermined steering angle or more, or a predetermined horizontal G or more.

CONSTITUTION: A 4WS.toe-in controller 10 moves a power rod 3 by a power cylinder 20 on the basis of the input information from a steering angle sensor, a vehicle speed sensor 13, and a G sensor 14, whereby rear wheels 1R are steered. In the power cylinder 20, the oil pressure from a pump 28 is supplied to and discharged from oil pressure chambers 24R, 24L through a rear wheel steering control valve 26 by passages 21R, 21L, and the pressure oil is supplied to and discharged from a central oil pressure chamber 23 through a toe-in control valve 27 by a passage 32. In this case, the toe-in control valve 27 is so controlled as to reduce the toe-in at the time of high speed when the rear wheel steering angle to the front wheel steering angle is small, while it prevents the interference of 4WS with the toe-in control.