Abstract: The present invention is designable on any thickness of magnesium thin plate, providing collectable power supply to the battery part of fuel body. The magnesium air battery 100 provides: the fuel body supply 200 including multiples of magnesium fuel bodies 101 that include magnesium; battery part 300 formed of conductive materials and an electrode that supplies electrons to oxygen; the disposal outlet 400, containing the fuel body integration part 401 that collects the exhausted magnesium fuel body 101; the fuel body holding frame 303, where the magnesium fuel body 101 is in a detachable hold, which moves through the fuel body supply 200, the battery part 300 and the disposal outlet 400.