REAR WHEEL STEERING DEVICE

PROBLEM TO BE SOLVED: To provide a rear wheel steering device capable of restoring a rear wheel in a straight-ahead direction even if a controlling means fails. SOLUTION: This rear wheel steering device, formed out of a screw member having a pair of screw parts which are threaded so as to oppose each other, a pair of slide members which are engaged with the pair of screw parts respectively and come into contact with or are separated from by an opposed screw action, and a steering shaft steering a pair of rear wheels, steers rear wheels by rotating the screw member with an electric motor and moving the steering shaft coupled with one slide member o one rear wheel side. This rear wheel steering device provided with controlling means 40, 50 controlling the electric motor and an electric motor driving means forward or backward driving the motor based on a signal from the controlling means 40, 50 a bridge circuit formed out or four switching elements involves a measure-against-failure circuit 70 which energizes, for a prescribed time, switching elements driving the electric motor in such a direction that a pair of side members comes nearer to each other if the controlling means 40, 50 fail.