MULTILAYER PIEZOELECTRIC ELEMENT, INJECTION APPARATUS, AND FUEL INJECTION SYSTEM

Provided is a multi-layer piezoelectric element capable of achieving a high response speed and an increase in the displacement amount, ensuring sufficient mechanical strength, and suppressing deterioration of characteristics. A multi-layer piezoelectric element (1) includes a stacked body in which piezoelectric layers (3) and internal electrode layers (5) are alternately laminated, and the piezoelectric layers (3) include a polarization domain (12) extending over a plurality of crystal particles (11). Since the piezoelectric layers (3) include the polarization domain (12) extending over the plurality of crystal particles (11), the multi-layer piezoelectric element (1) can achieve a high response speed and an increase in the displacement amount, ensure sufficient mechanical strength, and suppress deterioration of characteristics.