A semiconductor device and a method for fabricating the same, the device including an active pattern extending in a first direction on a substrate; a field insulating film surrounding a part of the active pattern; a first gate structure extending in a second direction on the active pattern and the field insulating film, a second gate structure spaced apart from the first gate structure and extending in the second direction on the active pattern and the field insulating film; and a first device isolation film between the first and second gate structure, wherein a side wall of the first gate structure facing the first device isolation film includes an inclined surface having an acute angle with respect to an upper surface of the active pattern, and a lowermost surface of the first device isolation film is lower than or substantially coplanar with an uppermost surface of the field insulating film.