A configuration is provided which includes a differential gear-type transfer ratio varying mechanism interposed between an input shaft which rotates as a steering wheel is operated and an output shaft which rotates in conjunction with operation of a steering mechanism for permitting a differential operation between both the shafts, the configuration including a transfer ratio control motor for applying a rotational force to the output shaft, a reaction force control motor for applying a rotational force to the input shaft, and a steering control unit for controlling and driving the transfer ratio control motor to obtain a rotation transfer ratio that is predetermined according to operation of the steering wheel and controlling and driving the reaction force control motor to apply a predetermined reaction force to the steering wheel.