Method of manufacturing an ultrasonic welding device and a disposable diaper using the same

To simplify the configuration and control for distancing or approach the ultrasonic horn and the anvil. Displacement mechanism includes a biasing mechanism for urging the output surface (6e) and the welding surface (10d) and an ultrasonic horn anvil roller (10) so as to approach to these normal direction (6), with has a guide surface which outer surface is pressed against the anvil roller to be located in the non-welding range (E2, E4) in (10) (21a, 23a) by the urging force of the energizing mechanism, and the pressed surface (21a) is a slit and a target pressing member (18) fixed to the sheet holding roller (5) in a state of being disposed within the width direction (6d). Guide surface (21a, 23a) of the pressing member (18), unwelded range anvil roller (10) from the welding range (E3) (E2, E4) output surface according to a movement to the (6e) welding surface (10d) and guides the anvil roller (10) away from each other.