A vibration welding device 40 includes: a vibration welding mold that is configured including an upper mold and a lower mold divided in an up-down direction, that is fitted with a first component and a second component forming an elongated shape having a bent portion, and that is disposed with length directions of the first component and the second component along a left-right direction; plural first mold divisions that configure one of the upper mold or the lower mold, and that are divided in the left-right direction; a pressing device that is coupled to each of the plural first mold divisions, and that applies pressure to the first mold divisions; and a vibration device that is coupled to each of the plural first mold divisions, and that vibrates the first mold divisions.