An apparatus for preventing data loss of a nonvolatile memory device and a method thereof are presented The apparatus includes a nonvolatile memory including a memory cell which writes bit information to a first page and a second page included in a first block using plural states which are implemented using at least 2 bits, and a data-processing unit which writes the bit information of the first page to a second block in the nonvolatile memory while the bit information is written to the second page after the bit information is written to the first page.