A control unit for driving a motor mainly includes an input circuit for inputting various kinds of information pieces, an output circuit for driving the coil windings of the motor, an MPU for calculating a control amount based on the information from the input circuit and outputting a control signal to the output circuit; the control unit has two pieces each of the input circuit, the output circuit, and the, and can supply respective electric currents to the windings of the motor or can cut off the supply; the MPUs each have a CPU incorporated therein, a trigger circuit for a trigger signal having a predetermined period; the two CPUs synchronize at least control commands in accordance with the trigger signal and output the control commands.