A semiconductor device includes a semiconductor layer and a trench gate portion that extends toward a deep portion from a front surface of the semiconductor layer. The semiconductor layer includes an island region surrounded by the trench gate portion. A first side surface of the trench gate portion and a second side surface of the trench gate portion are in contact with the island region. A first conductivity type contact region that includes a first contact region that is in contact with the first side surface and a second contact region that is in contact with the second side surface is provided in the island region. Moreover, a second conductivity type contact region that is in contact with the trench gate portion at a position between the first contact region and the second contact region is provided in the island region.