A non-volatile memory device including a memory cell array; a read/write circuit configured to drive bit lines of the memory cell array with a negative bit line voltage according to data to be programmed; a bit line setup-time measuring circuit configured to measure the bit line setup-time, which may be a function of the amount of data to be programmed, at each ISPP program loop; and a control logic configured to control the program voltage and/or the applied time of a program voltage applied to the selected wordline of the memory cell array based on the measured bit line setup-times measured at each ISPP program loop.