An ultrasonic welding device (1) for ultrasonically welding an object to be welded, comprising: a mechanical rotating support assembly that can rotate about a predetermined axis of rotation (L1) and can be operated to support the object on a circumference centered on the axis of rotation (L1), the object being supplied continuously； and at least one pair of a sonotrode (14) and an anvil (15) attached to the rotating support mechanical assembly to thereby rotate about the axis of rotation (L1) and insert the supported object onto the rotating support mechanical assembly to weld the object, when one between the sonotrode (14) and the anvil (15) is defined as a first welding tool and the other between the sonotrode (14) and the anvil (15) is defined as a second welding tool welding, the first welding tool being attached to the rotating mechanical support assembly so that it can move relative to the second welding tool between a position to interject the object in cooperation with the second welding tool and a position away from the second tool where the rotating support mechanical assembly includes a rotating element that can rotate about the axis of rotation (L1), characterized in that the mechanical support assembly gi The ration further includes a plurality of object support elements (44) each having a support surface to support the object, and a fixing mechanism (5c, 18) to allow the plurality of object support elements (44) joins the rotating element in a state in which the object support elements (44) are in the same circumference around the axis of rotation (L1), and allow adjusting the fixing positions of the object support elements ( 44) to the rotating member in radial directions centered on the axis of rotation, the ultrasonic welding device (1) includes a plurality of pairs of first and second welding tools； The rotating support mechanical assembly includes a plurality of second welding tool holding mechanisms (21) for respectively holding the plurality of
