First in this paper, the loss in piezoelectric ceramics is described. Antiresonance is the vibration under constant D (electric displacement) driving, and therefore electro-mechanical loss becomes almost zero: resonance is the vibration under constant E (electric field) driving, and then there exists large electro-mechanical loss. The relations between antiresonance and the constant D driving are explained. Next, a method of measuring the high-power characteristics is described for antiresonance frequency. Experimental results for the quality factor and temperature rise and other equivalent constants are then shown as high-power characteristics obtained at the antiresonance frequency. Finally, some considerations for the stable-state driving of the high-power piezoelectric devices are described.