According to the embodiment, the semiconductor device includes: a substrate; a stacked body; and a plurality of columnar portions. The stacked body is provided on the substrate. The stacked body includes a plurality of electrode layers stacked with an insulator interposed. The stacked body includes a stacked portion and a staircase portion. The plurality of electrode layers includes a first portion and a second portion. The columnar portions are provided in the stacked portion of the stacked body. The columnar portions extend in a stacking direction of the stacked body. The columnar portions include a semiconductor body extending in the stacking direction and a charge storage film. The second portion includes a third portion. A thickness of the third portion along the stacking direction is thinner than a thickness of the first portion along the stacking direction.