A nonvolatile memory device comprises a main memory cell array, a redundancy memory cell array, and a controller. The main memory cell array comprises a plurality of bit lines each connected to a plurality of strings arranged perpendicular to a substrate. The redundancy memory cell array comprises a plurality of redundancy bit lines each connected to a plurality of redundancy strings arranged perpendicular to the substrate. The controller is configured to control one of the redundancy bit lines to repair strings in the main memory cell array.