A semiconductor device includes a semiconductor part of a first conductivity type, a trench being provided in the semiconductor part at a front surface side; a first electrode provided on a back surface of the semiconductor part; a second electrode provided on the front surface of the semiconductor part; a first semiconductor layer of a second conductivity type provided inside the trench; and a insulating film electrically isolating the first semiconductor layer from the semiconductor part. The second electrode is electrically connected to the semiconductor part and the first semiconductor layer. The second electrode contacts the semiconductor part with a rectification property.