A high voltage power supply (HVPS) without an output voltage adjustment, a method of adjusting an output voltage of a HVPS, and an image forming apparatus using the method are provided. The image forming apparatus includes a high-voltage output unit that outputs a high voltage produced by the HVPS, a tag that stores an offset voltage information and is attached to the HVPS, and a high-voltage output control unit that reads the tag attached to the HVPS to extract the offset voltage information, and corrects a high-voltage output control signal by using the offset voltage information to change the high voltage output by the high-voltage output unit. Accordingly, a process of adjusting an output voltage of an HVPS as a single component is not required. The manufacturing costs of HVPSs are reduced, and the process of finely adjusting an output voltage of the HVPS is simplified.