A semiconductor device includes a semiconductor substrate having a first conductivity type, an epitaxial layer having a second conductivity type, an isolation area in the epitaxial layer to define an active area of the semiconductor substrate, a body area having a first conductivity type and a drift area having a second conductivity type adjacent to each other in the epitaxial layer, a LOCOS insulating layer in the drift area and surrounded by the drift area, a drain area adjacent to a side part of the LOCOS insulating layer and surrounded by the drift area, a body contact area and a source area in the body area and surrounded by the body area, and a gate area overlapping the drift area and a part of the LOCOS insulating layer from a direction of the body area.