Disclosed herein are a piezo actuator and a lens actuating module using the piezo actuator. The lens actuating module includes a housing having an accommodating space. A lens barrel is accommodated in the accommodating space. A preload unit includes a locking part locked to the outer circumference of the lens barrel and preload parts extending from both edges of the locking part outwards relative to the lens barrel. A piezo actuator is interposed between the preload parts and supported at a side thereof by force of the preload parts, the side being bent and deformed inwards and outwards, thus applying force for actuating the lens barrel in a direction of an optical axis to the preload unit. The piezo actuator which is simple in structure and assembling process and has improved actuating reliability and the lens actuating module using the piezo actuator are achieved.