Abstract: A plurality of first conductive layers are stacked at a predetermined pitch in a first direction perpendicular to a substrate. A memory layer is provided in common on side surfaces of the first conductive layers and functions as the memory cells. A second conductive layer comprises a first side surface in contact with side surfaces of the first conductive layers via the memory layer, the second conductive layer extending in the first direction. A width in a second direction of the first side surface at a first position is smaller than a width in the second direction of the first side surface at a second position lower than the first position. A thickness in the first direction of the first conductive layer at the first position is larger than a thickness in the first direction of the first conductive layer at the second position.