A non-volatile memory device, in which data values are determined by polarities at cell terminals, includes a memory cell array. The memory cell array is divided into multiple sub cell arrays, each sub cell array including at least one input/output line and an X-decoder/driver. First input/output lines included in different sub cell arrays may be simultaneously activated and bias voltages may be applied to the activated first input/output lines in accordance with the data values. The non-volatile memory device may be a bi-directional resistive random access memory (RRAM).