Abstract: In devices for the ultrasonic testing of a head screw inserted into a component, a skew position of an ultrasonic probe with respect to the screw head leads to inaccurate test results. In order to achieve precise test results independently of the position of the screwing-in axis, at least one ultrasonic transducer is disposed in a cradle-mounted centering piece of the ultrasonic probe. An adaptor of the centering piece is located nearer to the screw head than the ultrasonic transducer. The adaptor is matched to the configuration of the screw head. In order to achieve a centering connection with the screw head, the ultrasonic probe can be moved about its axis and in the axial direction. The device is principally to be used to test screws in the core baffle of a nuclear reactor vessel.