Provided is an ultrasonic welding device which carries out an ultrasonic weld process on a sheet-shaped member which is conveyed while being wound around the outer circumference face of a rotating member which rotates about a central axis. The ultrasonic welding device comprises the rotating member, and an ultrasonic processing unit which rotates about the central axis together with the rotating member. The ultrasonic processing unit further comprises a hone which ultrasound oscillates, and an anvil which sandwiches the sheet-shaped member together with the hone. At least one of the ultrasonic processing members, that is, the hone and/or the anvil, is guided to be capable of reciprocal movement in a CD direction which intersects the direction of the conveyance of the sheet-shaped member, and the ultrasonic processing member carries out reciprocal movement in the CD direction with respect to a portion of the sheet-shaped member which is wound about the rotating member. Both the hone and the anvil make contact with the sheet-shaped member in a prescribed zone in the CD direction upon the outer circumference face of the rotating member in both the outbound leg and the return leg of the reciprocal movement. The ultrasonic welding device further comprises an ultrasonic energy adjustment unit which makes the amount of ultrasonic energy (J/m) which is inputted per unit length in the CD direction in the prescribed zone in the outbound leg, to be different from the amount of ultrasonic energy (J/m) which is inputted per unit length in the CD direction in the prescribed zone in the return leg.L'invention concerne un dispositif de soudage ultrasonore qui réalise un processus de soudage ultrasonore sur un élément en forme de feuille qui est transporté tout en étant enroulé autour de la face circonférentielle externe d'un élément rotatif qui tourne autour d'un axe central. Le dispositif de soudage ultrasonore comprend l'élément rotatif et une unité de traitement ultrasonore qui
