IMAGE FORMING APPARATUS INCLUDING LAYER THICKNESS CONTROL PORTION TO CAUSE ROTATOR TO CARRY TONER, AND DEVELOPING DEVICE USED IN IMAGE FORMING APPARATUS

An image forming apparatus includes a rotator, a driving control portion, and a layer thickness control portion. The rotator conveys toner to contact position to an image carrying member, and supplies toner to the image carrying member at the contact position. The driving control portion controls rotation of the rotator so as to rotate the rotator during a developing period, and stop the rotation of the rotator after a set time has elapsed since an end of the developing period. The layer thickness control portion causes the rotator to carry toner by controlling a potential difference between a potential of the rotator and a predetermined potential so that toner on the rotator at the contact position has a first layer thickness during the developing period and has a second layer thickness while the rotation of the rotator is stopped, the second layer thickness being thicker than the first layer thickness.