A method for programming a non-volatile memory device includes programming a lower bit in a memory cell included in the non-volatile memory device, reading the lower bit programmed in the memory cell before programming an upper bit in the memory cell, determining a threshold voltage of the memory cell according to a result of reading the lower bit, determining a type of the memory cell using the threshold voltage, and supplying one of a plurality of pulses to a bit line connected to the memory cell according to the determined type of the memory cell.