Memory device for performing erase operation and operating method of the memory device

A memory device comprising:

• a cell string including memory cells coupled in series and coupled to word lines, respectively;
• a page buffer including latches coupled to the cell string through a bit line;
• and
• a page buffer controller configured to control the page buffer to input a masking bit to an input/output latch among the latches and perform a data transfer operation by moving the masking bit to other latches except the input/output latch, among the latches.

A method of operating a memory device comprising a page buffer including an input/output latch, a transfer latch, and a sensing latch, the method comprising:

• inputting a masking bit to the input/output latch;
• moving a value input to the input/output latch, to the transfer latch;
• moving the value, moved to the transfer latch, to the sensing latch;
• moving the value moved to the sensing latch, back to the input/output latch;
• outputting the value moved back to the input/output latch;
• and
• determining a bit line coupled to the page buffer as a masking fail column, based on a result of comparing an output value with the masking bit.