Provided is a rear wheel toe angle control system that can prevent the impairment of the tracking performance of the electric actuator and enable the rear wheel toe angle control system to ensure the stability of the vehicle even when the electric actuator for steering the rear wheel according to the operating condition of the vehicle is subjected to an axial force. An ECU (12) serving as a rear wheel toe angle control unit for variably controlling the rear wheel toe angle (δr) of the motor vehicle (V) by using an electric actuator (11) is provided with a duty ratio correcting unit (25) that corrects the target duty ratio (Dtgt) for achieving the target rear wheel toe angle (δrtgt) according to the load condition of the electric actuator (11) that depends on the lateral acceleration (Gy) of the motor vehicle (V).