Image forming apparatus and cartridge mountable on the same

An image forming apparatus comprising:

• a cartridge including a photosensitive member, a frame configured to support the photosensitive member so that the photosensitive member is rotatable, and a pressing portion;
• and
• a main body including a fixing portion that includes a heating rotation member and that heat-fixes a toner image on a sheet, and a mounting portion on which the cartridge is mounted,
• the fixing portion including a fixing shutter configured to be movable between a first position where a part of the heating rotation member is covered and a second position where the part of the heating rotation member is exposed,
• the fixing shutter including a force receiving portion configured to receive a force for the fixing shutter to move from the first position to the second position,
• wherein while the cartridge is being mounted on the mounting portion, the pressing portion of the cartridge presses the force receiving portion of the fixing shutter to move the fixing shutter from the first position to the second position.