Electronic device including first plate including first flat surface portion facing first direction, wherein first plate forms first surface of electronic device; second plate including second flat surface portion facing second direction opposite first direction, wherein second plate forms second surface of electronic device; side member including first metal part including first metallic material and forming at least part of third surface between first surface and second surface and second metal part including second metallic material, wherein second metal part is bonded with first metal part; and display disposed between first plate and the second plate so as to be shown through the first plate, wherein the first metal part and the second metal part form an interface including the first metallic material and the second metallic material, and wherein the interface is configured to face a third direction that is perpendicular to the first direction and the second direction.