A method for driving a plasma display panel having discharge gaps formed by a plurality of first electrodes and a plurality of second electrodes, the method including: measuring a load ratio of an input video signal inputted to the plasma display panel; applying a greatest number of discharge pulses with a maximum gradient to the first electrodes and the second electrodes if the load ratio of the video signal is less than the threshold value; and reducing a luminance of the plasma display panel by gradually adjusting the gradient of at least one of the sustain discharge pulses to a lower inclination and/or declination level (or a gentle level).