An image forming apparatus has an exchangeable process cartridge which transfers a toner image from a latent image carrier onto a sheet. The process cartridge includes a frame; an endless latent image carrier provided on the frame; a charger provided on the frame for charging the latent image carrier; a transfer roller rotatably provided at a portion of the frame which faces the latent image carrier; and a cover for the transfer roller having guide ribs which guide a paper sheet. The transfer roller transfers a toner image from the latent image carrier onto a sheet. The image forming apparatus includes an endless latent image carrier; a latent image forming unit forming an electrostatic latent image on the latent image carrier; a developing unit for developing the electrostatic latent image on the latent image carrier; a transfer roller for transferring a toner image from the latent image carrier onto a sheet; and a process cartridge having a protection cover member for rotatably supporting at least the latent image carrier on a frame and rotatably holding the transfer roller opposing the latent image carrier.