A rear side surface of a frame of an image-forming apparatus has throttle portions protruding toward the inside of the frame. By aligning the screw holes in the throttle portions and the through-holes in a guide rail and then screwing screws into these holes, the guide rail is fixed to the rear side surface with a predetermined distance therebetween. This restricts deformation of the guide rail due to a load applied by opening and closing the document holding plate.