A semiconductor device according to the present invention includes: a semiconductor layer of a first conductivity type; an annular deep trench penetrating the semiconductor layer in the depth direction to surround an element forming region; a drain region of a second conductivity type formed in a surface layer portion of the semiconductor layer in the element forming region; a drift region of the second conductivity type formed in the surface layer portion of the semiconductor layer to come into contact with the drain region in the element forming region; a body region of the first conductivity type formed in the surface layer portion of the semiconductor layer at an interval from the drift region in the element forming region; a source region of the second conductivity type formed in a surface layer portion of the body region; and a first high-concentration buried region, formed in the semiconductor layer between a portion opposed to the source region in the depth direction and the deep trench, having a higher impurity concentration than that of the semiconductor layer.