According to one embodiment, a semiconductor device includes a plurality of first semiconductor regions of a first conductivity type, a plurality of second semiconductor regions of a second conductivity type, a third semiconductor region of the second conductivity type, a fourth semiconductor region of the second conductivity type, a fifth semiconductor region of the first conductivity type, and a gate electrode. An impurity concentration of the second conductivity type of the third semiconductor region is higher than an impurity concentration of the second conductivity type of the second semiconductor regions. The fourth semiconductor region is provided on the first semiconductor regions. The gate electrode provided on the fourth semiconductor region with a gate insulation layer interposed. The gate electrode extends in a third direction. The third direction intersects the first direction. The third direction is parallel to a plane including the first direction and the second direction.