The invention relates to an ultrasonic actuator (2) with a polarization axis P, said actuator being made of a piezoelectric ceramic. The ultrasonic actuator (2) has a temperature expansion coefficient which is parallel to the polarization axis P and which differs from a temperature expansion coefficient that is perpendicular to the polarization axis P, and at least one friction element (8) is arranged on the ultrasonic actuator. The friction element (8) consists of an anisotropic monocrystal with temperature expansion coefficients which are different along the three crystal axes a, b, and c. The temperature expansion coefficient along a first of the three crystal axes is the lowest, and the temperature expansion coefficient along a second of the three crystal axes is the greatest. The friction element (8) is aligned relative to the ultrasonic actuator (2) such that the first crystal axis is parallel to the polarization axis P of the ultrasonic actuator (2), and the second crystal axis is perpendicular to the polarization axis P of the ultrasonic actuator (2). The invention additionally relates to an ultrasonic motor with an ultrasonic actuator of the aforementioned type.