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