Provided is a metal-air battery including a cathode having an air path. The metal-air battery includes a plurality of folded cells stacked in a direction, and each of the folded cells includes: an anode having a U-shape defined by first and second portions separated from and parallel to each other, and a side portion which connects the first and the second portions to each other; an anode protection film arranged on an inner surface of the anode; and a first cathode and a second cathode on the anode protection film, the first cathode and the second cathode arranged facing each other between the first portion and the second portion of the anode. The first cathode and the second cathode each includes a base which contacts the anode protection film, and a plurality of protrusion units extended from the base.