PURPOSE: To remove excess toner in the developer and achieve the stabilization of image quality by charging photoreceptor then developing the same with the developer thence recovering the toner powder on the photoreceptor.

CONSTITUTION: When toner concentration is too high, a toner recovery mode is selected prior to copying operation. In this mode, an exposure device 3, paper feeders 28, 29, transfer device 5, destaticizing separator 6 and toner replenishing device 19 are disabled. First, a photosensitive drum 1 is charged by a charger 2 and the toner is deposited on the photosensitive drum 1 by a developing device 4. This toner is straightly carried to a cleaning device 7, where it is removed by a cleaning blade 23. The removed toner passes through a conveyor 27 and is recovered into the toner replenishing device 19. In this way, the excess toner in the developer may be removed without requiring any special device and the degradation of image quality such as ground stains prevented.