An image forming apparatus and a cartridge are provided. The image forming apparatus includes a main casing, a CPU as a judgment unit, and a main electrode. The cartridge accommodating a toner is attachable to and detachable from the main casing, and has a cartridge electrode electrically connectable to the main electrode. The CPU is configured to judge assembly or non-assembly of the cartridge with respect to the main casing and to judge whether or not the assembled cartridge is a new cartridge. The cartridge electrode is movable by a predetermined moving amount to permit the main electrode to be movable. As a result of a movement of the main electrode in accordance with the movement of the cartridge electrode, the CPU determines that the assembled cartridge is a new cartridge.