Provided is an ultrasonic processing device which has a simple structure and which is for performing ultrasonic processing on a web which is travelling in a machine direction, in the width-ways direction of said web. In an ultrasonic processing device (50), a web (31) is made to continuously travel in a machine direction (MD) by means of an upstream-side conveyance means (51) and a downstream-side conveyance means (52). Between the means (51, 52) an operating surface of a first machine component, which is a fixed component in the device (50), extends in a direction which obliquely intersects with the machine direction (MD). The web (31) travels in the machine direction (MD) above the operating surface. A second machine component is provided in the device (50), with said component facing the operating surface and moving in a direction which obliquely intersects with the machine direction. The operating surface of the first machine component, and the second component work together to perform ultrasonic processing on the web (31). One among an ultrasonic horn (63) and an anvil (68) is used in the first machine component, and the other among the ultrasonic horn and the anvil is used in the second machine component.La présente invention concerne un dispositif de traitement ultrasonore qui a une structure simple et qui est utilisé pour effectuer un traitement ultrasonore sur une bande qui se déplace dans une direction machine, dans la direction transversale par rapport à ladite bande. Dans un dispositif de traitement ultrasonore (50), une bande (31) est amenée à se déplacer en continu dans une direction machine (MD) par le biais de moyens de transport côté amont (51) et de moyens de transport côté aval (52). Entre les moyens (51, 52) une surface opérationnelle dun premier composant de machine, qui est un composant fixe dans le dispositif (50), sétend dans une direction qui coupe obliquement la direction machine (MD). La bande (31) se déplace dans la direction machine (MD)
