In a color printing mode of an image forming apparatus, two toner images in respective colors are formed and superimposed on an intermediate transfer belt. A gap D11 between toner images of the same color is narrowed while a gap D12 between toner images of different colors is widened, thereby corresponding to the switching of developers. In a printing mode that forms a monochrome image using one developer, gaps D21, D22 between the respective toner images are the same. In a printing mode that forms a monochrome image while switching four developers, a toner image formed immediately before the switching is shifted forward, thereby widening a gap D34 from the next toner image.