A composite membrane includes: an organic layer including a plurality of through holes; and ion conductive inorganic particles disposed in the plurality of through holes, wherein the ion conductive inorganic particles each include at least one recess, at least one protrusion, or a combination thereof on a surface thereof, and wherein the surface of the ion conductive inorganic particles which comprises the at least one recess, the at least one protrusion, or the combination thereof faces a surface of the organic layer.