The invention relates to an ultrasonic welding device having an oscillator, having a sonotrode, which can be caused to oscillate with a wavelength, and has a welding region in the vibration antinode of the sonotrode. The sonotrode is supported at the vibration node of the sonotrode in a first bearing. To enable both a radial and an axial alignment of the sonotrode, the first bearing has a projection, which has a U-shaped geometry in a section extending in a longitudinal direction of the sonotrode, which U-shaped geometry has side legs and a cross leg that connects the side legs, the projection engages in a recess in the sonotrode matched to the U-shaped geometry, the sonotrode is supported on the cross leg of the projection in a planar manner, and the sonotrode is axially aligned by means of at least one side leg of the projection.