An image forming apparatus includes a main assembly and a cartridge. The main assembly includes a mounting portion for mounting the cartridge and a door for causing the mounting portion to be in an open state and a closed state. The main assembly or the cartridge includes an expansion and contraction member for displacing at least a part of the cartridge. Opening and closing of the door is interrelated with expansion and contraction of the expansion and contraction member. In the closed state, the cartridge mounted in the mounting portion is in a first position, inside the main assembly, where an image is formable. In the open state, the cartridge mounted in the mounting portion is in a second position where at least a part thereof projects to an outside of the main assembly.