A semiconductor device includes first and second active regions. Each active region includes a plurality of fin protrusions and a recessed area disposed between the fin protrusions. A plurality of gate structures are disposed on each of the plurality of fin protrusions. A semiconductor layer is disposed in each recessed area. A distance between the gate structures of the first active region is the same as a distance between the gate structures of the second active region, and a height difference between a bottom surface of the semiconductor layer of the first recessed area and a top surface of each of the fin protrusions of the first active region is smaller than a height difference between a bottom surface of the semiconductor layer of the recessed area of the second active region and a top surface of each of the fin protrusions of the second active region.