When driving sustaining discharge in a PDP of four-electrode structure, it is possible to improve luminance and reduce power consumption by devising the drive method especially for a Z-electrode. In the plasma display device, when driving sustaining discharge for the PDP from a controller and a driver, switching is performed between the sustaining discharge for applying a narrow pulse to the Z-electrode and the sustaining discharge for applying a fixed potential to the Z-electrode according to judgment of the display load ratio region.
