A method of manufacturing a wiring structure may include forming a first conductive pattern on a substrate, forming a hardmask on the first conductive pattern, forming a first spacer on sidewalls of the first conductive pattern and the hardmask, forming a first sacrificial layer pattern on a sidewall of the first spacer, forming a second spacer on a sidewall of the first sacrificial layer pattern, removing the first sacrificial layer pattern, and forming a third spacer on the second spacer, may be provided. The third spacer may contact an upper portion of the sidewall of the first spacer and define an air gap in association with the first and second spacers. The first spacer has a top surface substantially higher than a top surface of the first conductive pattern. The second spacer has a top surface substantially lower than the top surface of the first spacer.