An image forming apparatus in which respective color visible images on tandem-arrayed
plural photoconductor drums are sequentially overlay-transferred onto an intermediate
transfer belt by application of a primary transfer voltage by intermediate transfer
rollers, then the images are transferred at a time from the belt onto a print sheet
by application of a secondary transfer voltage by a paper transfer roller. The
same primary transfer voltage is applied to the respective color intermediate transfer
rollers from one power source. In the intermediate transfer belt, a relative dielectric
constant, a surface resistance and a volume resistance are controlled such that
potential charged by initial transfer is attenuated to or lower than the
transfer voltage before a belt position of the initial transfer arrives at a next
transfer position.
