A position of a stretch roller, where the stretch roller stretches an intermediate transfer belt upstream of and adjacently to a most upstream primary transfer roller in a rotational direction of the intermediate transfer belt, is apart from a photosensitive drum with respect to a primary transfer surface. Further, the most upstream primary transfer roller is larger in outside diameter than other primary transfer rollers, and the most upstream primary transfer roller has a transfer pressure larger than the transfer pressure of the other primary transfer rollers. This arrangement inhibits the most upstream primary transfer roller from deforming and a defective transfer due to waving of the intermediate transfer belt, while inhibiting an increase in size of an apparatus.