Provided is a lightweight anvil roller and an ultrasonic welding device provided therewith. The anvil roller has: a supported section that is rotatably supported by a holding mechanism via a rotary shaft in such a manner that the anvil roller can come into rolling contact with a sheet; an outer peripheral section having a welding surface over which the sheet is welded between the outer peripheral section and an ultrasonic horn during rolling contact with the sheet; a thin section that is formed between the supported section and the outer peripheral section in such a manner that the thickness of the thin section is smaller than the thickness of the outer peripheral section in the axial direction of the rotary shaft; and a vibration proof member provided on the thin section.