In a PDP, a waveform which has a reset function, an address function, and a sustain discharge function to a scan electrode while a sustain electrode is biased at a constant voltage. The waveform includes a voltage which corresponds to a difference between a voltage applied to the scan electrode and a voltage applied to the sustain electrode in the general driving waveform. As a result, a board for driving the sustain electrode is eliminated, and a combined board is realized.