Electric power steering system

An electric power steering system according to the present invention comprises: a sensor module (1) including a steering torque sensor (12) and a control circuit (13) housed therein; and a motor module (2) including an electric motor (M) and a motor driving circuit (14) housed therein. The sensor module (1) and the motor module (2) are physically separately mounted in the electric power steering system. Since the sensor module (1) and the motor module (2) are physically separated, these modules can separately be produced, and the steering torque sensor (12) and the electric motor (M) can independently be adjusted (Fig. 1).