A steering ECU includes a plurality of microcomputers to control a motor. A main communication line for communicating a main command value and a subsidiary communication line for communicating a subsidiary command value are connected to each of the microcomputers. The steering ECU includes an abnormality detecting circuit configured to detect a normal state, a semi-normal state detected during the normal state, or an abnormal state detected during the semi-normal state as a communication state of each communication line. When the normal state is detected for the main communication line, the abnormality detecting circuit is configured to set use of the main command value. When the semi-normal state or the abnormal state is detected for the main communication line, the abnormality detecting circuit is configured to set use of the subsidiary command value under a condition that the normal state is detected for the subsidiary communication line.