A semiconductor memory device has a plurality of gates vertically stacked on a top surface of a substrate, a vertical channel filling a vertical hole that extends vertically through the plurality of gates, and a memory layer in the vertical hole and surrounding the vertical channel. The vertical channel includes a bracket-shaped lower portion filling part of a recess in the top of the substrate and an upper portion extending vertically along the vertical hole and connected to the lower channel. At least one end of an interface between the lower and upper portions of the vertical channel is disposed at a level not than that of the top surface of the substrate.