A nonvolatile memory device includes a mold structure having a stack of word lines on a substrate and first and second string selection lines on the word lines, a first cutting structure through the mold structure, a second cutting structure through the mold structure, the second cutting structure being spaced apart from the first cutting structure, a channel structure penetrating the mold structure to be connected to the substrate, the channel structure being between the first and second cutting structures, a first cutting line cutting through the first string selection line but not through the second string selection line, the first cutting line being between the first and second cutting structures, and a second cutting line cutting through the second string selection line but not through the first string selection line, the second cutting line being between the second cutting structure and the channel structure.