In one embodiment, the non-volatile memory device includes a plurality of normal memory cells, and at least one flag memory cell associated with one of the plurality of normal memory cells. A normal page buffer is configured to store data read from one of the plurality of normal memory cells. The normal page buffer includes a main latch storing the read data. A control circuit is configured to selectively change data stored in the main latch during a read operation based on a state of the flag memory cell.