Example embodiments provide a method and apparatus of correcting error data due to charge loss within a non-volatile memory device including a plurality of memory cells. The method of correcting error data within the non-volatile memory devices may include detecting error data in a second data group by comparing a first data group read from memory cells in response to a first voltage with the second data group read from memory cells in response to a second voltage. The second voltage is higher than the first voltage. Error data in the first data group is detected by error-correcting code (ECC). Re-writing data in the memory cells is performed by correcting error data in the first data group and error data in the second data group. A central processing unit (CPU) may detect error in the second data group. The second data group may be read through a page buffer and compared with the first data group stored in a SRAM. The detected error may be updated to the page buffer. Error data in the first data group may be updated to the page buffer. The CPU corrects error in the final error data, and the page buffer rewrites the corrected data in the plurality of memory cells.