A driving method of a plasma display panel for gray-scale display using subfields, in each of which an address step, a sustaining discharge step, and a reset step are performed. The method includes dividing the unit frame into unit drive periods corresponding to the number of gray scales, trisecting each unit drive period into a unit address period, a unit sustaining discharge period, and a unit reset period, dividing each unit address period into the same number of time intervals as there are subfields and allocating the divided time intervals to the respective subfields, starting the respective subfields sequentially with a time interval corresponding to the unit drive period and overlapping one another, and applying an address voltage between the scan electrode line and the address electrode line corresponding to the first unit drive period of the subfields during the time interval allocated to each unit address period, applying a sustaining discharge voltage between the common electrode lines and all the scan electrode lines during all the unit sustaining discharge periods, and applying a reset voltage between the common electrode lines and the scan electrode lines corresponding to the last unit drive period of the subfields during each unit reset period.