A non-volatile memory may include a flag cell array, wherein each flag cell is arranged in the memory cell array interspersed among the plurality of memory cells. The flag cell array may include a plurality of flag cells indicating whether a corresponding row is MSB programmed. The non-volatile memory device performs an algorithm to read out data stored in the memory cell based on whether the memory cells of a row are MSB programmed. When determining whether the corresponding row is MSB programmed, a flag cell that is not normally operated may be replaced by a redundancy flag cell or data of the flag cell that is not normally operated may be excluded. Thus, the reliability in reading out of data and the production yield of the non-volatile memory may be improved.