In a sustain operation in an ALIS PDP device, a combination in which a basic first waveform and a second waveform in which a discharge peak is separated are mixed is applied. In the combination, the probability that the second waveform occurs successively is sufficiently reduced to less than 20%, and the number of times of sustain discharges of various intensities is made equal in the lines to be driven. By this means, the 2L nonuniformity can be prevented, and the deterioration of Vsmin can be reduced.