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