A semiconductor device including air gaps and a method of fabricating the same. The semiconductor device in accordance with an embodiment may include a bit line structure having a bit line formed over a first contact plug, a second contact plug formed adjacent to the first contact plug and the bit line structure, an air gap structure comprising two or more air gaps to surround the second contact plug and have an outer sidewall in contact with the bit line structure, and one or more capping support layers separating the air gaps, a third contact plug capping a part of the air gap structure and being formed over the second contact plug, and a capping layer for capping a remainder of the air gap structure.