An image display device includes a pair of sustain pulse generators for applying either a first sustain pulse or a second sustain pulse to the display electrodes. The first and second sustain pulses generate a sustain discharge twice and once, respectively, in discharge cells when the voltage applied between the display electrodes changes. The application of the first sustain pulse is performed by generating a first discharge by applying a voltage to one of the display electrodes using the clamp corresponding to the one of the display electrodes, and then generating a second discharge by applying a voltage to the other of the display electrodes using the clamp corresponding to the other of the display electrodes. The application of the second sustain pulse is performed by generating a first discharge by applying a voltage to each of the display electrodes using the clamps corresponding to each of the display electrodes.