A piezoelectric actuator includes a piezoelectric bending transducer, the first end of the bending transducer may be pivoted, while its second end, which is opposite to the first end, may be movably supported in a longitudinal transducer direction. Given a simultaneously large deflection path or bending lift, the actuator may attain a high restoring or working force. Thus, in the case of a valve piezoelectrically actuated by such an actuator, the sealing effect of a valve channel, which is closed or to be closed, may be significantly increased.