A method of operating a non-volatile memory device includes storing one or more addresses of word lines (WLs), but not the entire addresses of the WLs, into a latch, the WLs disposed between a string selection line (SSL) and a ground selection line (GSL), selecting a first WL from the latch, performing an erasing operation on memory cells associated with the string selection line (SSL), the memory cells associated with the SSL constituting a memory block, and verifying the erasing operation on memory cells associated with the selected first WL.