A semiconductor device includes an interlayer insulating layer disposed on a substrate, a first metal wiring and a second metal wiring disposed in the interlayer insulating layer, the first and second wirings spaced apart from each other in a first direction, the first and second wirings extending to a second direction perpendicular to the first direction, an air gap formed in the interlayer insulating layer between the first metal wiring and the second metal wiring, and spaced apart from a sidewall of the first metal wiring and a sidewall of the second metal wiring, and a capping layer disposed on the interlayer insulating layer, the capping layer covering the first metal wiring, the second metal wiring, and the air gap, wherein the air gap is disposed at a first distance from the first metal wiring in the first direction and at a second distance from the second metal wiring in the first direction, and wherein the first and second distances are the same.