A power semiconductor device includes a semiconductor substrate having a plurality of trenches formed in an upper surface thereof; a buried insulating film; a buried field plate electrode; a control electrode; a first main electrode provided on a lower side of the semiconductor substrate; and a second main electrode provided on an upper side of the semiconductor substrate. The semiconductor substrate includes: a first semiconductor; a second semiconductor layer of the first conductivity type and a third semiconductor layer of a second conductivity type; a fourth semiconductor layer; and a fifth semiconductor layer. The buried insulating film is thicker than a gate insulating film. At least one of the second semiconductor layer and the third semiconductor layer has a portion with its sheet dopant concentration varying along a depth direction of the semiconductor substrate.