According to one embodiment, a semiconductor device includes first to third electrodes, first to fourth semiconductor regions, and a first insulating portion. The first semiconductor region includes first to third partial regions. The first partial region is provided between the first electrode and the second electrode. The second partial region is provided between the first and third electrodes. The second semiconductor region includes fourth to sixth partial regions. The fourth partial region is provided between the first partial region and the second electrode. The fifth partial region is provided between the third semiconductor region and at least a portion of the second partial region. The sixth partial region is provided between the third partial region and the third semiconductor region. The fourth semiconductor region is provided between the first and fourth partial regions. The first insulating portion is provided between the second partial region and the third electrode.