A nonvolatile memory device includes a 3D memory cell array having words lines that extend from a lowest memory cell array layer closest to a substrate to a highest memory cell array layer farthest from the substrate, a voltage generator circuit generating first and second voltage signals, and a row selecting circuit that simultaneously applies the first voltage signal to a selected word line and the second voltage signal to an unselected word line. The selected word line and the unselected word line have different resistances, yet the first voltage signal is applied to the selected word line and the second voltage signal is applied to the unselected word line with a same rising slope over a defined period of time.