A pulse width modulator for use in a digital amplifier, includes a pop noise reducer for reducing pop noise by controlling a width and a phase of a pulse of a PWM signal output from the pulse width modulator, wherein the pop noise reducer contains: a PWM pulse register for storing a width and a phase values of a pulse of the PWM signal; and a pulse generator for outputting the PWM signal according to the values stored in the PWM pulse register. The pulse width modulator reduces pop noise generated when power supply to a digital amplifier is started and interrupted.