A semiconductor device includes a semiconductor substrate which functions as an n− drift layer, a trench IGBT formed in the front surface, an interlayer insulator film, and a metal electrode layer on the interlayer insulator film. There is a contact hole in the interlayer insulating film which has a first opening formed on the metal electrode layer side and a second opening on the semiconductor substrate side. Width w1 of the first opening on the metal electrode layer side is wider than width w2 of first opening on the semiconductor substrate side, in a direction perpendicular to the extending direction of the trench in the planar pattern of trenches. The metal electrode layer is connected to a p-type channel region and an n+ source region via the contact hole. The method of manufacturing improves the reliability of the device.