Semiconductor device

A semiconductor device includes a substrate including first and second active regions, a first active pattern on the first active region, a second active pattern on the second active region, a device isolation layer filling a trench between the first active pattern and the second active pattern, the device isolation layer having a concave top surface, a first gate electrode in the first active region, a second gate electrode in the second active region, a gate cutting pattern disposed between the first gate electrode and the second gate electrode and separating the first gate electrode and the second gate electrode, and an insulating pattern between the gate cutting pattern and the concave top surface of the device isolation layer.