A photosensitive-member unit includes a plurality of photosensitive members arranged in a first direction. The photosensitive-member unit is movable in the first direction to be mounted to or dismounted from a mount position in an apparatus main body. A positioning member is fixed to the apparatus main body and is configured to contact the photosensitive-member unit when the photosensitive-member unit is mounted at the mount position, thereby positioning the photosensitive-member unit at the mount position relative to the apparatus main body. A friction applying member is provided to one side of the apparatus main body with respect to a second direction perpendicular to the first direction. The photosensitive-member unit is configured to slidingly contact the friction applying member when the photosensitive-member unit moves to the mount position, allowing the friction applying member to apply a frictional force to the photosensitive-member unit.