A memory device comprises a memory cell array comprising a plurality of memory blocks each comprising a plurality of memory cells and a control setting circuit. The control setting circuit divides the memory blocks into at least first and second groups based on whether each of the memory blocks comprises at least one substandard memory cell, and sets individually control parameters of the first and second groups. The substandard memory cells are identified based on test results of the memory cells with respect to at least one of the control parameters. Each memory block in the first group comprises at least one substandard memory cell, and each memory block in the second group comprises no substandard memory cell.