A method of manufacturing a semiconductor device includes forming an active pattern and a gate electrode crossing the active pattern on a substrate, forming a first contact connected to the active pattern at a side of the gate electrode, forming a second contact connected to the gate electrode, and forming a third contact connected to the first contact at the side of the gate electrode. The third contact is formed using a photomask different from that used to form the first contact. A bottom surface of the third contact is disposed at a level in the device lower than the level of a top surface of the first contact.