A semiconductor device includes a plurality of trench gates provided abreast in a semiconductor substrate; an interlayer insulation film having opening from which a part of a front surface of the semiconductor substrate is exposed; and contact plugs provided in the openings. The interlayer insulation film comprises a plurality of first portions, each of which covers a corresponding one of the trench gates, and a plurality of second portions, each of which is provided between adjacent first portions and along a direction intersecting with the first portions. The openings are provided at an area surrounded by the first portions and the second portions, a length of the openings in a direction along the first portions is shorter than a length of the openings in a direction along the second portions intersecting with the first portions.