A copying machine is provided with a transfer belt which is in contact with the surface of a photosensitive drum and which is made to run in an endless manner. A transfer roller and an auxiliary roller are arranged inside the region defined by the transfer belt. The transfer roller is in contact with the transfer belt, defining a transfer nip therebetween. The transfer nip is part of a conveyance nip defined between the drum surface and the transfer belt, and is located downstream of the region just under the photosensitive drum. The auxiliary roller is located downstream of the conveyance nip. The contact between the drum surface and the transfer belt defines a posterior-transfer conveyance nip located downstream of the transfer nip with respect to the running direction of the transfer belt, and also defines a prior-transfer conveyance nip located upstream of the transfer nip with respect to the same direction. The width of the posterior-transfer conveyance nip is less than that of the prior-transfer conveyance nip. With this structure, satisfactory transfer characteristics are maintained, and yet the separation characteristics of recording sheets with reference to the drum surface can be improved. Accordingly, images of good quality can be output.