PURPOSE: To make the constitution of a device compact and to realize the high speed operation by providing an electrical conductive toner carrier which is biased to polarity which is reverse to the electrostatic charge characteristic of toner and a supply means which supplies a toner thin film on the toner carrier in a developing device.

CONSTITUTION: A photosensitive body 1 is obtained by disposing successively a light transmissive conductive layer 12 and a photoconductive layer 13 on a light transmissive substrate 11. An electrode roller is electrically conducted to the layer 12 of the body 1 and electrically coupled to a bias power source 10 at the same time. Besides, a prescribed bias is given to the layer 12 of the body 1. Then, electric charge is induced by bringing an induction member into contact with the surface of the body 1. By irradiating the surface of the body 1 with light beams corresponding to different colors from the substrate 11 side and giving the toner of the color corresponding to the concerned color to the layer 13 side, a multicolor toner image is formed. By a developing device 35 or the like, the respective toner of magenta, cyan, yellow, black or the like whose polarity is reversed to an electrostatic charge image is given to the body 1. Besides, the toner thin layer is supplied on the toner carrier by the supply means.