To provide an image forming device by which an image having an excellent quality is formed by preventing the occurrence of insufficient transfer and a print image due to the change of the inner surface resistance value of an intermediate transfer body to whose primary or secondary transfer means a constant electric charge is supplied by a constant current supplying means.

This device is composed of the intermediate transfer body 2 turning while it is opposed to the toner image carrying surface 1a of an image carrier 1, the primary transfer means 3 performing primary transfer to the intermediate transfer body 2, the secondary transfer means 4 performing secondary transfer to a body to be transferred (P), the constant current supplying means 5 to supply the primary transfer means 3 or the secondary transfer means 4 with a constant current, a grounding means 6 to ground both sides of an entrance to go in and out of the transfer bias applying part (T) of a turning intermediate transfer body 2 and a leaked current detecting/replenishing means 7 to replenish a shunt current by detecting a current value meaning a flowing leaked current to the grounding means 6 and feeding back to the constant current supplying means 5.