A semiconductor device and a method of fabricating the same, the semiconductor device includes a plurality of fin shaped structures, a trench, a spacing layer and a dummy gate structure. The fin shaped structures are disposed on a substrate. The trench is disposed between the fin shaped structures. The spacing layer is disposed on sidewalls of the trench, wherein the spacing layer has a top surface lower than a top surface of the fin shaped structures. The dummy gate structure is disposed on the fin shaped structures and across the trench.