A setting unit sets a high-voltage set value. A first generation unit generates a high voltage based on the set value set by the setting unit and a first reference voltage supplied from a supply unit. A second generation unit generates a second reference voltage by being supplied with the first reference voltage from the supply unit. A comparing unit compares the first reference voltage with the second reference voltage. A storage unit stores a comparison result that has been obtained in advance by the comparing unit comparing the first reference voltage with the second reference voltage. A correction unit corrects the high-voltage set value based on a comparison result that is obtained by the comparing unit when the image forming apparatus is in use and the comparison result that has been obtained in advance and is stored in the storage unit.