A metal-air battery includes a gas diffusion layer; a first cathode and a second cathode disposed on opposite surfaces of the gas diffusion layer, respectively; an ion conducting membrane, including a folded portion, surrounding the first cathode, the gas diffusion layer, and the second cathode and disposed on each of the first cathode and the second cathode; and an anode, including a folded portion, surrounding the ion conducting membrane and disposed on the ion conducting membrane, where the folded portion of the anode is folded in a same direction as the folded portion of the ion conducting membrane.