Method of operating non-volatile memory device

PURPOSE: A method for operating a nonvolatile memory device is provided to improve the retention characteristic of the memory device by re-programming data in a memory block. CONSTITUTION: First data is read from a first memory block and is saved in a page buffer part(210). Second data is read from a second memory block and is saved in the page buffer part. Third data is read form a third memory block and is saved in the page buffer part. Data saved in the page buffer part is programmed in a temporary memory block(220). The memory blocks are erased. Whether the read memory block is the last memory block is verified(230). One block address for selecting memory blocks is increased(240).