An electronic control unit reads a side slip angle of a vehicle body. Next, the electronic control unit reads a correction amount entered by a driver. Next, the electronic control unit calculates a target steering angle by subtracting a correction term from a rotation amount of a steering output shaft, which has a predetermined relation with a rotation amount of a steering input shaft, to reduce a lateral force generated in the vehicle due to the side slip angle of the vehicle body. Subsequently, the electronic control unit drives and controls an electric motor of a variable-gear-ratio actuator until the rotation amount of the steering output shaft reaches the target steering angle.