A semiconductor device includes a substrate having a first region and a second region, first active fins that extend in a first direction in the first region, second active fins that extend in the first direction in the second region, a first field insulating layer between the first active fins and that extend in a second direction, a second field insulating layer between the second active fins and extending in the second direction, a gate line that extends in the second direction on the second field insulating layer, the gate line linearly along with the first field insulating layer, a gate isolation layer between the first field insulating layer and the gate line, and gate spacers that extend in the second direction, the gate spacers in contact with both sidewalls of each of the first field insulating layer, the gate line, and the gate isolation layer.