A nonvolatile memory device can improve its operation characteristic by reducing leakage current of a bit line in a read operation. The nonvolatile memory device includes a plurality of word lines, a plurality of main bit lines intersecting with the plurality of word lines, a plurality of cell blocks each including a plurality of cell strings, each of the cell strings including first and second select transistors and a plurality of memory cells, a plurality of sub bit lines commonly connected to the respective cell strings in same group, the cell blocks being grouped into a plurality of groups whose number is identical to or smaller than the number of the cell blocks, a plurality of group selectors configured to selectively connect the main bit lines to the sub bit lines of a selected group, and a plurality of page buffers configured to sense data of the memory cells through the main bit lines.