A high voltage power supply for use in a laser printer, multifunction peripheral, or similar device, wherein the high voltage power supply includes a pulse width modulation (PWM) input unit, a high voltage output unit, and a delaying feedback unit for preventing the generation of an abnormally high voltage in an output signal of the high voltage output unit. By delaying the time when an offset voltage is supplied to the output signal, the generation of an abnormally high voltage that is applied to a surface of a photoconductive drum when a printer is turned on and which can deteriorate the quality of printed images can be prevented.