A semiconductor device includes a substrate, a first stacked film and a second stacked film each including insulating layers and electrode layers alternately provided on the substrate, and columnar portions provided in the insulating layers and electrode layers of the first stacked film, and including charge storage layers and semiconductor layers. The second stacked film further includes an insulator including first and second lower faces, the first lower face is inclined by a first angle to an upper face of one of the electrode layers in the first stacked film, the second lower face is inclined by a second angle to the upper face of the one of the electrode layers in the first stacked film, and the second angle is less than the first angle. The insulating layers and electrode layers in the second stacked film are provided below the first and second lower faces of the insulator.