A piezoelectric stack (1) has alternately successive piezoelectric layers (2) and inner electrode layers (3, 4) which are alternately electrically connected to two outer electrodes (7, 8) which are arranged on the outer side (5, 6) of the piezoelectric stack (1). The piezoelectric stack (1) also has at least one safety layer (9, 40, 50) which is arranged between two successive piezoelectric layers (2) instead of one of the inner electrode layers (3, 4). The safety layer (9, 40, 50) is structured in such a manner that it has an internal interruption (13, 44, 45, 53) which is configured in such a manner that the safety layer (9, 40, 50) does not form an electrical contact between the two outer electrodes (7, 8) if it contact-connects both outer electrodes (7, 8) and is electrically conductive.