A circular piezoelectric apparatus includes an electrode assembly which has an independent electrode located on a perimeter side wall of the circular piezoelectric apparatus and two separated electrodes located respectively at two opposite surfaces of the circular piezoelectric apparatus, a first structure located between the two separated electrodes that has a polarized direction coincided with a first axial direction directing from one electrode of the two separated electrodes to the other electrode thereof, and a second structure surrounding the first structure about the first axial direction and having a polarized direction coincided with a radial direction of the perimeter. One of the three electrodes is electrically connected a ground electrode to provide a voltage source for supplying an input voltage and a load through at least a conductive wire, and another electrode is electrically connected to an input electrode of the voltage source through another conductive wire.