Abstract: In a rear wheel steering device for a front and rear wheel steering system of a wheeled vehicle wherein rear wheels are steered by displacement of tie rods connected to the knuckles of the rear wheels and disposed in the lateral direction of the vehicle in an opposite phase relationship relative to the front wheels at least under a certain condition such as a small steering angle or a low vehicle speed, the centers of the turning radii of the rear wheels are made to coincide with each other by determining the geometry of the tie rods and the knuckle arms in such a manner that a pair of imaginary lines formed by connecting the pivot points between the knuckle arms and the tie rods to the points of intersection between a horizontal plane containing the said pivot points and the center lines of rotation of the knuckles relative to the vehicle body intersect at a point which is located ahead of the center line of the rear wheel axle.