A branch structure of a laminated flat electric wire includes: a laminated flat electric wire in which two or more plate-shaped flat electric wires are laminated; and a branch box. The laminated flat electric wire has tabs each extending from each of the flat electric wires. Each of the tabs is provided with a hole. The branch box has the same number of rod-shaped members as the number of tabs, and the rod-shaped members are disposed at positions corresponding to the positions of the holes of the tabs. Two or more laminated flat electric wires are fixed to each other by passing each of the rod-shaped members through a corresponding hole of the tabs in a state where the two or more laminated flat electric wires extend from the branch box in opposite directions from each other or directions orthogonal to each other.