Disclosed is an electronic device. The electronic device includes a housing that includes a first plate facing a first direction, a second plate facing a second direction opposite the first direction, and a side housing surrounding a space between the first plate and the second plate, wherein the second plate includes an outer surface facing the second direction and being substantially flat and an inner surface facing the first direction and being substantially flat, an inner plate interposed between the first plate and the second plate, wherein the inner plate includes a surface facing the inner surface of the second plate and an opening, an antenna structure comprising a substrate including a first surface facing the inner surface of the second plate and a second surface facing away from the inner surface, at least one conductive pattern on the first surface and/or embedded in the substrate, a surrounding portion including a hole penetrating the second surface, the antenna structure being disposed in the opening, and a support coupler including a protrusion extending to an interior of the hole.