A semiconductor device includes a semiconductor substrate of a first conductivity type, a first region of a second conductivity type formed in the semiconductor substrate, a second region of the first conductivity type formed in the first region, a source region of the second conductivity type formed in the second region, a drain region of the second conductivity type formed in the first region, a first junction part including a part of a border between the first region and the second region, which is on the side of the drain region, a second junction part including a part of the border between the first region and the second region, which is at a location different from the first junction part, a gate electrode formed above the first junction, and a conductor pattern formed above the second junction part and being electrically independent from the gate electrode.