Abstract: In a method of reprogramming data in a nonvolatile memory device including a plurality of pages each of which includes a plurality of memory cells, first page data programmed in a first page is read from among a plurality of page data programmed in the plurality of pages. The plurality of page data have a threshold voltage distribution including a plurality of states. An error correction code (ECC) decoding is performed on the first page data. A reprogram operation is selectively performed on target bits in which an error occurs among a plurality of bits included in the first page data based on a result of performing the ECC decoding on the first page data and a reprogram voltage. The target bits correspond to a first state among the plurality of states. A voltage level of the reprogram voltage is adaptively changed.