The present invention provides a PWM control device wherein a microprocessor detects the rotational position of rotor of a brushless motor with respect to the amount of each current supplied from an inverter circuit for driving the brushless motor to the brushless motor and outputting of a PWM signal through the use of its detected signal to thereby perform PWM control. Upon startup of the brushless motor under the PWM control, the pulse width of the PWM signal is enlarged during interrupt processing including a process for detecting the rotational position of rotor of the brushless motor, and the pulse width of the PWM signal is progressively enlarged according to the repetition of the interrupt processing. It is thus possible to easily suppress an overshoot current with respect to the current supplied to the motor upon startup of the motor.