<p>An image forming device, wherein visible images of various colors on a plurality of photoconductive drums arranged in tandem are successively superposed on an intermediate transfer belt and transferred thereto by application of a primary transfer voltage through an intermediate transfer roller and then collectively transferred to a paper sheet from the belt by application of a secondary transfer voltage through a paper sheet transfer roller. Each color transfer roller has the same primary transfer voltage applied thereto in common from the same power supply. The intermediate transfer belt has its relative dielectric constant, surface resistance and volume resistance adjusted so that the potential electrified by the initial transfer may decrease to not more than 1/3 of the transfer voltage before the next transfer position is reached.</p>
