According to one embodiment, a semiconductor device includes a first electrode, a second electrode, first to fourth semiconductor regions and a first insulating film. The second electrode includes first, second, and third electrode regions. The first semiconductor region includes first, second, third, fourth, and fifth partial regions. The first partial region is separated from the first electrode. The second partial region is separated from the first electrode region. The fourth partial region is separated from the second electrode region. The second semiconductor region includes sixth, seventh, eighth and ninth partial regions. The third semiconductor region is connected to the second semiconductor region. The fourth semiconductor region is electrically connected to the second electrode. The fourth semiconductor region includes tenth, eleventh, and twelfth partial regions. The first insulating film is provided between the first, third, and fourth semiconductor regions.