PURPOSE: To prevent the consumption of developer by lowering developing bias voltage to almost zero potential and stopping the electrostatic latent image carrier from driving when an action stopping signal is inputted during image forming and after the time required to move a point on an electrostatic latent image carrier from an electrifying position to a developing position has passed.

CONSTITUTION: When the action stopping signal is inputted during the image forming, an electrifying means 2 is stopped except when jamming occurs near the electrostatic latent image carrier 1 and after the time required to move the point on the electrostatic latent image carrier 1 from the electrifying position P1 to the developing position P2 has passed, the developing bias voltage Vb is lowered to the almost zero potential to stop the electrostatic latent image carrier 1 from driving. Therefore, when a drive stopping signal is inputted, almost the same potential difference as a one during developing is kept between the electrostatic latent image carrier 1 and a developing sleeve 15 until the developing position P2 part passes from the electrifying position P1 to the developing position P2 so as not to supply a carrier to the electrostatic latent image carrier 1 from the developing sleeve 15. Thus, the consumption of the developer can be prevented.