Provided is a semiconductor device. The semiconductor device comprises a first active pattern extending in a first direction on a substrate, a second active pattern which extends in the first direction and is adjacent to the first active pattern in a second direction different from the first direction, a field insulating film placed between the first active pattern and the second active pattern, a first gate structure which crosses the first active pattern, extends in the second direction, and includes a first gate electrode and a first gate spacer, a second gate structure which crosses the second active pattern, extends in the second direction, and includes a second gate electrode and a second gate spacer, a gate separation structure placed on the field insulating film between the first gate structure and the second gate structure.