A nonvolatile memory device with improved product reliability and a method of fabricating the same is provided. The nonvolatile memory device comprises a substrate, a first mold structure disposed on the substrate and including a plurality of first gate electrodes, a second mold structure disposed on the first mold structure and including a plurality of second gate electrodes and a plurality of channel structures intersecting the first gate electrodes and the second gate electrodes by penetrating the first and second mold structures, wherein the first mold structure includes first and second stacks, which are spaced apart from each other, and the second mold structure includes a third stack, which is stacked on the first stack, a fourth stack, which is stacked on the second stack, and first connecting parts, which connect the third and fourth stacks.