In an image forming apparatus that is provided with a developing unit to develop an electrostatic latent image formed on an image carrier as a toner image, the developing unit is provided with a developer reservoir that is disposed between a supplying roller to feed developer agitated by an agitating member into the developer reservoir and a developing roller to cause the developer in the developer reservoir to adhere onto the latent image on the image carrier so as to be developed as the toner image. A control section controls driving of the supplying roller, independently from driving of the agitating member.