In a plasma display device and driving method thereof, middle electrodes are formed between X electrodes for receiving a sustain pulse voltage and Y electrodes. A reset waveform and a scan pulse voltage are applied to the middle electrodes. A short-gap discharge is performed between the X electrode and the middle electrode in the earlier stage of a sustain discharge period, and a long-gap discharge is normally performed between the X electrode and the Y electrode after the earlier stage of the sustain discharge period, thereby performing stable discharge. Further, the number of switches of the M electrode driver may be reduced by floating the M electrode and applying a rising ramp waveform to the Y electrode in the reset period, thereby increasing the voltage at the M electrode.