A metal-air battery includes first and second cells, each cell including a negative electrode metal layer, a negative electrode electrolytic film, a positive electrode layer configured to use oxygen as an active material, and a gas diffusion layer, wherein the negative electrode metal layer, the negative electrode electrolytic film, the positive electrode layer, and the gas diffusion layer are sequentially disposed, wherein each cell has an open surface through which at least a portion of the gas diffusion layer is in fluid communication with, outside air, wherein the first and second cells contact each other, and wherein a direction of a first open surface of the first cell is different from a direction of a second open surface of the second cell.