The present invention concerns an ultrasonic welding installation comprising an ultrasonic vibration unit having a sonotrode and a converter, wherein the sonotrode and the converter are arranged in mutually adjacent relationship along a longitudinal axis and the ultrasonic vibration unit can be caused to resonate with an ultrasonic vibration in the direction of the longitudinal axis with a wavelength λ, wherein there can be provided an amplitude transformer arranged between the sonotrode and the converter, wherein there is provided a holder for holding the ultrasonic vibration unit. To provide an ultrasonic welding installation having a holder which allows simple adjustment of the ultrasonic vibration unit and simple replacement thereof it is proposed according to the invention that the holder has a clamping device which is reciprocable between an opened position in which the ultrasonic vibration unit can be removed from the holder and a closed position in which the clamping device comes into contact with the ultrasonic vibration unit and exerts a force on same so that the ultrasonic vibration unit is held.