A motor control apparatus provided with an inverter for successively commutating the current to a motor using a PWM signal; a PWM signal generating device for generating the PWM signal using a carrier signal; a rotational state quantity sensor for detecting a rotational state quantity; a phase difference detecting device for detecting the phase difference between the carrier signal and the rotational period based on the rotational state quantity; a frequency setting device for setting a frequency of the carrier signal to a value in accordance with a multiplier for one period in terms of electrical angle of the rotational period of the motor, when the rotational frequency is equal to or greater than a specified frequency and the phase difference is equal to or less than a specified value; and a synchronizing device for synchronizing a control period of the carrier signal to the rotational period.