According to one embodiment, a semiconductor device includes first to third electrodes, first to third semiconductor regions, first and second insulating parts, and a gate electrode. The first semiconductor region is provided on the first electrode. The second semiconductor region is provided on the first semiconductor region. The third semiconductor regions are provided selectively on the second semiconductor region. The first insulating part is arranged with the third and second semiconductor regions, and a portion of the first semiconductor region. The second electrode is provided inside the first insulating part. The gate electrode is provided inside the first insulating part and electrically isolated from the second electrode. The third electrode is provided on the second and third semiconductor regions. The third electrode includes a contact part provided between the third semiconductor regions. The second insulating part is provided between the first semiconductor region and the contact part.