According to one embodiment, a semiconductor device includes first and second regions, a first insulating portion, and first, second, and third electrodes. The first region includes first and second partial regions, and a third partial region between the first and second partial regions. The second region includes fourth and fifth partial regions. The fourth partial region overlaps the first partial region. The fifth partial region overlaps the second partial region. The first insulating portion includes first, second, and third insulating regions. The first insulating region is provided between the second insulating region and the third partial region and between the third insulating region and the third partial region. The first electrode is electrically connected to the fourth partial region. The second electrode is away from the first electrode and is electrically connected to the fifth partial region. The third electrode is provided between the first and second electrodes.