Abstract: A rear-wheel steering system is provided in a four-wheel steering vehicle having at least a front-wheel steering angle sensor, a vehicle speed sensor, a control unit for carrying out rear-wheel steering control in dependency on signals detected by these sensors, and an electric motor controlled by the control unit to steer the rear wheels. This rear-wheel steering system is provided with detecting means for detecting front-wheel steering force, front-wheel lateral force or lateral acceleration of the vehicle. The control unit is provided with a front-wheel neutral point correction means for determining the zero point of the front-wheel steering angle which causes the rear-wheel steering angle to be zero with respect to a signal indicating that the front-wheel steering force, the front-wheel lateral force or the lateral acceleration of the vehicle thus detected by the detecting means is substantially zero.