An object of the present invention is to improve safety of a motor by instantaneously detecting the abnormality of a PWM signal. To achieve the object, provided is a motor control microcomputer for outputting PWM signals to a motor drive circuit driving a motor, which includes an abnormal signal detection circuit and a PWM signal stop circuit. The abnormal signal detection circuit receives inputs of positive-phase and negative-phase signals of the PWM signals, detects that both of the positive-phase and negative-phase signals are at the H level, and then outputs detection signals. The PWM signal stop circuit receives the detection signals from the abnormal signal detection circuit, and stops the outputs of the PWM signals.