An image forming apparatus includes a main assembly provided with an opening; a drawer movable while supporting an cartridge including a photosensitive drum between an inside position and an outside position; an optical unit in the main assembly to project light onto the drum a shutter member provided in the main assembly and movable between a closing position and an open position an operating portion to move the shutter member from the open position to the closing position in a process of movement of the drawer from the inside position to the outside position and to move the shutter member from the closing position to the open position in a process of movement of the drawer from the outside position to the inside position.