Driving device, driving method, and plasma display device

A first ramp waveform (RW1) of which an electric potential increases from a first electric potential (Vscn) to a second electric potential (Vscn + Vset) in a first period (t5 to t6) is applied to a plurality of scanning electrodes (SCi). A driving waveform of which the electric potential decreases from a third electric potential (Ve1) to a fourth electric potential (0 V) before the first period (t5 to t6) and in the first period (t5 to t6), the electric potential is kept to the fourth electric potential (0 V) is applied to a plurality of sustain electrodes (SUi). At this time, a second ramp waveform (RW10) of which an electric potential starts to increase at the same time as the start time (t5) of the first period (t5 to t6) and increases from a fifth electric potential (0 V) to a sixth electric potential (vd) according to the electric potential change of the first ramp waveform (RW1) in a second period (t5 to t5a) that is shorter than the first period (t5 to t6) is applied to a plurality of data electrodes (