A vertical-type nonvolatile memory device is provided in which differences between the sizes of channel holes in which channel structures are formed are reduced. The vertical-type nonvolatile memory device includes a substrate having channel hole recess regions in a surface thereof. Channel structures vertically protrude from the surface of the substrate on ones of the channel hole recess regions, and memory cell stacks including insulating and conductive layers are alternately stacked along sidewalls of the channel structures. A common source line extends along the surface of the substrate on other ones of the channel hole recess regions in a word line recess region, which separates adjacent memory cell stacks. Related fabrication methods are also discussed.