According to one embodiment, a semiconductor device includes first to third regions, and first to third electrodes. The first region includes a first partial region, a second partial region, and a third partial region between the first and second partial regions. A direction from the first partial region toward the first electrode is aligned with a first direction. A direction from the second partial region toward the second electrode is aligned with the first direction. A second direction from the first electrode toward the second electrode crosses the first direction. A direction from the third partial region toward the third electrode is aligned with the first direction. At least a portion of the third region is provided between the first and second electrodes in the second direction. At least a portion of the second region is provided between the third and first regions.