An image forming apparatus includes an image supporting member for forming a developer image; a developing unit for forming a developer layer and forming the developer image on the image supporting member using developer of the developer layer; a developer supplying unit for supplying the developer to the developing unit; an image density detection unit for detecting an image density of the developer image; and a control unit for controlling a voltage applied to the developing unit and the developer supplying unit. The control unit corrects the voltage applied to at least one of the developing unit and the developer supplying unit according to the image density detected with the image density detection unit.