A semiconductor device in which an interlayer insulation film covers striped gate electrodes with a thickness larger than a thickness of a gate oxide film. The interlayer insulation film includes first contact holes outside each striped trench, and second contact holes inside the striped trench. In a plan view, striped active regions and striped contact regions both extending in a longitudinal direction exist. The striped active regions and the striped contact regions are alternately and repeatedly disposed in a direction perpendicular to the longitudinal direction. In each of the striped active regions, the source electrode is connected to a source region through the first contact hole. In each of the striped contact regions, the source electrode is connected to a protective diffusion layer through the second contact hole.