An electronic control unit includes two inverters, a magnetic sensor, a failure detection unit, an inverter driving unit, a signal examination unit, and a failed element identification unit. The magnetic sensor detects a magnetic flux generated around a winding. The failure detection unit detects an ON-state failure of the inverter. When the ON-state failure is detected, the inverter driving unit stops driving the inverter to which the ON-state failure has been detected, and continues driving the other inverter. The signal examination unit examines a presence or absence of a special signal. When there is a signal appearing according to a special magnetic flux, the failed element identification unit identifies a failed switching element based on a motor electric angle generated by the signal.