Disclosed is a semiconductor device comprising a substrate, a plurality of active patterns that protrude from the substrate, a device isolation layer between the active patterns, and a passivation layer that covers a top surface of the device isolation layer and exposes upper portions of the active patterns. The device isolation layer includes a plurality of first isolation parts adjacent to facing sidewalls of the active patterns, and a second isolation part between the first isolation parts. A top surface of the second isolation part is located at a lower level than that of top surfaces of the first isolation parts.