A piezoelectric drive unit is configured for driving a passive element relative to an active element, wherein the active element includes a resonator with two arms, each extending in parallel to a reference plane and ending in a contact element, which is movable by oscillating movements of the arms and thereby drives the passive element. A pre-stress element is arranged to exert a relative force between the active element and passive element, pressing them against one another with pre-stress forces that are normal to the reference plane.