A semiconductor memory device includes a stacked structure on a substrate and a vertical structure penetrating the stacked structure. The stacked structured includes a plurality of conductive lines stacked on the substrate. The vertical structure may include a vertical insulating pattern and a channel film extending along sidewalls of the vertical insulating pattern. The vertical insulating pattern may include an inner region and an outer region. The outer region of the vertical insulating pattern may be placed between the channel film and the inner region of the vertical insulating pattern, and the outer region of the vertical insulating pattern may include a diffused metal.