Piezoelectric actuator having at least three piezo-elements (2a-2d), at least two of which are operated as working elements (20a, 20b), which perform a linear forward or backward movement, wherein at least one of the working elements (20a, 20b) mechanically expands in a longitudinal direction for performing the forward movement and for performing the backward movement, and another of the working elements (20a, 20b) contracts in the longitudinal direction, characterised in that - the piezo-elements (2a-2d) are arranged inside a carriage in a longitudinal direction, said carriage performing the movement in the forward or backward direction; - a fixedly arranged counter bearing is provided between two of the piezo-elements (2a-2d), on which counter bearing the piezo elements (2a-2d) are supported during operation, and - a control device (10, 11) is provided which is set up in such a way that: it operates at least one further piezo-element (2a-2d) as a setting element (20c, 20d) and, in doing so, is controlled in such a way that the whole piezo-element arrangement inside the carriage is mechanically pre-tensioned and the piezoelectric actuator assumes a corresponding zero position as a consequence, and it controls the working elements (20a, 20b) in a subsequent working phase in such a way that at least one of the working elements (20a, 20b) mechanically expands in a longitudinal direction for performing the forward movement and for performing the backward movement of the carriage, and another of the working elements (20a, 20b) contracts in the longitudinal direction. - the piezo-elements (2a-2d) are arranged inside a carriage in a longitudinal direction, said carriage performing the movement in the forward or backward direction; - a fixedly arranged counter bearing is provided between two of the piezo-elements (2a-2d), on which counter bearing the piezo elements (2a-2d) are supported during operation, and - a control device (10, 11) is provided which is set up in such a way that: it operates at least one further piezo-element (2a-2d) as a setting element (20c, 20d) and, in doing so, is controlled in such a way that the whole piezo-element arrangement inside the carriage is mechanically pre-tensioned and the piezoelectric actuator assumes a corresponding zero position as a consequence, and it controls the working elements (20a, 20b) in a subsequent working phase in such a way that at least one of the working elements (20a, 20b) mechanically expands in a longitudinal direction for performing the forward movement and for performing the backward movement of the carriage, and another of the working elements (20a, 20b) contracts in the longitudinal direction. it operates at least one further piezo-element (2a-2d) as a setting element (20c, 20d) and, in doing so, is controlled in such a way that the whole piezo-element arrangement inside the carriage is mechanically pre-tensioned and the piezoelectric actuator assumes a corresponding zero position as a consequence, and it controls the working elements (20a, 20b) in a subsequent working phase in such a way that at least one of the working elements (20a, 20b) mechanically expands in a longitudinal direction for performing the forward movement and for performing the backward movement of the carriage, and another of the working elements (20a, 20b) contracts in the longitudinal direction.