According to one embodiment, a semiconductor device includes first, second, third electrodes, a semiconductor member, and a first compound member. The third electrode is between the first and second electrodes in a first direction from the first to second electrodes. The semiconductor member includes first and second semiconductor regions. The first semiconductor region includes first, second, third, fourth, and fifth partial regions. A second direction from the first partial region to the first electrode crosses the first direction. The fourth partial region is between the first and third partial regions in the first direction. The fifth partial region is between the third and second partial regions in the first direction. The second semiconductor region includes first and second semiconductor portions. The first compound member includes first, second and third compound regions.