A joint structure includes a reinforcement portion that is formed by joining a composite material and a reinforcing material through an adhesive. The composite material includes a plate portion that is formed by laminating a plurality of fiber sheets, and a raised portion that is formed by laminating a plurality of fiber sheets in addition to the plurality of fiber sheets of the plate portion, and surfaces of the plate portion and the raised portion are covered with a single fiber sheet. The reinforcement portion includes the raised portion and the reinforcing material that is bonded to the raised portion through an adhesive. A first boundary between the plate portion and the raised portion and a second boundary between the raised portion and the reinforcing material are located at different positions in an in-plane direction of a laminated interface between the fiber sheets that are laminated.