An image forming apparatus includes a main assembly, an operating portion provided slidably between a first position and a second position of the main assembly, a supporting position, a slide rail, a slidable member, and an urging unit. A relationship of engagement between the slide rail and the slidable member is set so that the engagement between the slide rail and the slidable member when the operating portion is in a position between the first position and the second position is looser than the engagement between the slide rail and the slidable member when the operating portion is in the first position or the second position.