A standard cell comprises a first active region and a first power rail, the first active region and the first power rail disposed in a first MOS region; a second active region and a second power rail, the second active region and the second power rail disposed in a second MOS region; and a gate electrode extending to cross the first and second active regions and the first and second power rails in a first direction, wherein the first power rail is disposed closer to a boundary between the first MOS region and the second MOS region than to a first side of the first MOS region opposite the boundary, and wherein the second power rail is disposed closer to the boundary between the first MOS region and the second MOS region than to a first side of the second MOS region opposite the boundary.