According to one embodiment, a semiconductor device includes a stacked body in which a plurality of conductive layers and a plurality of insulating layers are alternately stacked. The semiconductor device includes a mark and a supporting unit. The mark is opened onto a surface of the stacked body. The supporting unit is provided around the mark. The supporting unit extends in a stacked direction of the stacked body. The supporting unit is in contact with at least a plurality of conductive layers.