An image forming apparatus including a setting memory storing multiple voltage settings; two or more voltage applying members each contacting a voltage applied member at respective contact positions close to each other, which are simultaneously being applied with respective voltages selected from the voltage settings; two or more current detectors each detecting a current flowing in the respective contact positions; and a setting changer performing a setting changing processing in which the voltage applied to one of the voltage applying members is changed based on the current detected by the corresponding current detector while a predetermined voltage is applied to the other voltage applying members, so that an optimum current flows in the corresponding contact position.