There is provided a joint body including: a reinforcing member having at least one random layer in which a chopped carbon fiber is randomly oriented in a thermoplastic resin, and at least one unidirectional material layer in which a continuous carbon fiber is unidirectionally arranged in a thermoplastic resin; and a reinforced member with an open sectional shape having at least one selected from the group consisting of a random layer and a unidirectional material layer, wherein the reinforcing member and the reinforced member are vibration-welded to form a hollow closed section.