One of aspects of the present invention is to provide an image forming apparatus includes an intermediate transfer member rotating at a first circumferential speed, and an image carrier capable of having a plurality of toner images formed thereon in turn, each of the toner images having a color different from one another, for transferring the toner images onto the intermediate transfer member, the image carrier rotating at a second circumferential speed. At least one of the first and second circumferential speeds are adjustable in accordance with a driving mode selected from a group consisting of a monochrome mode and a color mode. Also, a first difference between the first and second circumferential speeds in the monochrome mode is greater than a second difference between the first and second circumferential speeds in the color mode.