Most conventional piezoelectric vibratory gyroscopes have been constructed by using the bending vibrations as in a tuning-bar or a tuning-fork oscillator. However, this kind of vibratory gyroscope faces substantial practical problems because its vibration characteristics usually are easily influenced by the support or lead installation of the element. In contrast, if the trapped-energy vibrations are used because they have a high degree of concentration of the vibration energy and a nonvibrating region over a wide range, these problems would be solved at once, and highly precise and reliable piezoelectric vibratory gyroscopes could be implemented. In this paper, we propose a trapped-energy vibratory gyroscope with three electrodes, which uses the thickness-shear vibrations excited by a parallel electric field in a partially polarized piezoelectric ceramic plate, as the structure for this type of trapped-energy vibratory gyroscope and describe the principle of construction for the gyroscope. First, the energy trapping of thickness-shear vibrations in a partially polarized piezoelectric ceramic plate, which is the basic theory of the vibratory gyroscope, is theoretically analyzed and the mechanism and characteristics of energy trapping are clarified. Next, based on these results, the experimental results for the piezoelectric vibratory gyroscope using a partially polarized piezoelectric ceramic plate 1.5 mm thick are presented. © 2001 Scripta Technica, Electron Comm Jpn Pt 2, 84(3): 44–52, 2001