A semiconductor device has: a semiconductor substrate; a trench that extends from a first surface of the semiconductor substrate towards an interior of the semiconductor substrate, and that has a recess/protrusion structure on a side wall surface thereof; a semiconductor film that is formed so as to cover the side wall surface of the trench, be continuous with the side wall surface, and extend onto the first surface of the semiconductor substrate; an opposite electrode having a first portion that is provided at a position opposing the semiconductor substrate while sandwiching the semiconductor film therebetween, and that extends on the first surface of the semiconductor substrate, and a second portion that is continuous with the first portion and extends so as to fill the trench; and an insulating film that insulates the semiconductor film from the opposite electrode.