A piezoelectric vibratory gyrosensor, constructed using a trident tuning-fork resonator, is characterized by superior support construction. That is, for a trident tuning-fork, the vibrational loss with its support condition becomes so small that a gyrosensor has good performance compared with other existing type resonators. First, the vibration modes of a trident tuning-fork have been investigated, and suitable clamping conditions are clarified using finite-element analysis. Then, the method of adjusting the resonance frequencies between driving and detecting vibration modes and the influences of arm imbalance were studied. Moreover, when detecting the angular rates using a prototype trident tuning-fork resonator, the leakage output signal was apparently eliminated by connecting a differential circuit. As a result, a small-sized piezoelectric vibratory gyrosensor having good gyro-characteristics could be measured.