PURPOSE: To keep the electrostatical charge quantity of a replenished toner adequately by providing a transfer speed control means to lower the transfer speed of the toner and a carrier with the transfer and agitation means which is synchronized with replenishing the toner.

CONSTITUTION: While lowering the rotational speed of a rotation means 13 of a screw 12 with a controller 20, which is synchronized with a toner replenishing part 19, the transfer speed of the toner and carrier with the screw 12 is made late. The replenished toner and carrier are transferred slowly along a transfer passage 11, and the supplied toner and carrier are sufficiently agitated, while they are led to the supplying section 14 of the edge part and the replenished toner is sufficiently electrified with frequent contacts with the carrier. The charge capacity of the freshly replenished toner is raised and when in this state an image formation is conducted, the formed image has no fogging and also the scattering of the toner is eliminated, as well.