An image-forming apparatus includes: image-holding members each holding an image and being rotatable around a rotation shaft; a frame member that partially defines a space for accommodating the image-holding members; a cover that opens and closes the space, an inner side of the cover having rotation shaft insertion holes; a supporting shaft that supports the cover so the cover is pivotable with respect to the frame member; and a positioning mechanism that positions the cover when the cover closes the space. The positioning mechanism includes at least two projections that project from either the frame member or the cover and are spaced apart in a direction of an axis of the supporting shaft such that lengths of perpendicular line segments from the two projections to the axis of the supporting shaft are different from each other. Projection insertion holes receive the corresponding projections when the cover is closed.