In a control unit, a control part is operated by electric power from an ignition power supply, and controls operations of relays and inverters. A first end of a boosting part is electrically connected between at least one relay and a corresponding inverter. A second end of the boosting part is electrically connected to the control part. The boosting part boosts a voltage at the first end, and outputs the voltage boosted from the second end. An abnormality detecting portion detects an abnormality of the boosting part. When the abnormality detecting portion detects an abnormality of the boosting part, the control part controls the at least one relay to which the first end of the boosting part is connected to shut off a flow of electric power from a main power supply to the boosting part and to the inverter corresponding to the at least one relay.