Patent ID: 8410663

Claim:
A piezoelectric actuator unit comprising: a multi-layer piezoelectric element having a plurality of piezoelectric layers and a plurality of metal layers, the piezoelectric layers and the metal layers being stacked one on another; and a case which houses the multi-layer piezoelectric element, wherein the plurality of metal layers comprise an internal electrode and a stress relieving layer which comprises a plurality of metal particles and voids, the metal particles being scattered throughout the entire region between two piezoelectric layers which adjoin the stress relieving layer in the direction of stacking, wherein the plurality of metal particles are scattered so as to be electrically separated from each other by the voids, and wherein a part of the plurality of metal particles are separated from the piezoelectric layer to form a peel-off section at least in a part of the interface between the stress relieving layer and the piezoelectric layer that adjoins therewith.