Piezostacks are capable of producing very large forces, but they provide only limited displacements. Thus, the displacement amplification mechanism is necessary to make those actuators more efficient and useful. For this purpose, a two-bridge-type flexure hinge mechanisms in series in a three-dimensional structure is proposed in this study. To show the validity of the proposed mechanism, the kinematic analysis is carried out by a matrix method and by a finite element method, and then the amplification ratio derived from both methods were compared with the simple geometric ratio, which is an order of magnitude too high. Along with this analysis, displacement and frequency experiments are also performed to verify the analysis results. The displacement errors between the matrix analysis results and experimental ones are within 10%. This indicates that the deformation of the flexure hinge in the parasitic direction should be considered for more exact estimation of amplification ratio of the bridge-type hinge mechanism. At last, the performance of this actuator is analyzed using the matrix model with respect to design parameters. The results show that the performance of a piezoactuator can be improved with the optimization of hinge parameters for each application requirement. (C) 2003 American Institute of Physics.