A nonvolatile memory device and method of fabricating same, the nonvolatile memory device including a substrate; a first semiconductor layer on the substrate; an etching stop film including a metal oxide on the first semiconductor layer; a mold structure including second semiconductor layers and insulating layers alternately stacked on the etching stop film; a channel hole penetrating through at least one of the mold structure, the etching stop film, the second semiconductor layer and the substrate; and a channel structure extending along a side wall of the channel hole, including an anti-oxidant film, a first blocking insulation film, a second blocking insulation film, a charge storage film, a tunnel insulating film and a channel semiconductor sequentially formed along the side wall of the channel hole. The first semiconductor layer contacts the first blocking insulation film, the second blocking insulation film, the charge storage film, and the tunnel insulating film.