An operation of reducing a voltage at a scan electrode by as much as a predetermined voltage and floating the scan electrode is repeatedly performed in a reset period of a plasma display panel. When the voltage at the scan electrode is reduced and a discharge is generated, a discharge extinction is generated when the scan electrode is floated, and the voltage at the scan electrode increases. At this time, the voltage increase of the scan electrode is applied and the voltage at the scan electrode is greatly reduced when the voltage at the scan electrode is subsequently reduced.