In a connecting structure (20), a metal lever (21) and a metal link (22) are connected to each other via a metal pin (connecting pin) (23). The metal lever (21) has a circular connecting hole (21a). The metal pin (23) includes a support shaft portion (23a) insertable through the connecting hole (21a), pivotable and movable in an axial direction of the metal pin by a preset amount with respect to the connecting hole (21 a), a head portion (23b) formed at one end portion of the support shaft portion (23a), and a connecting shaft portion (23c) formed at the other end portion of the support shaft portion (23a). The metal link (22) has a coupling hole (22a) fitted to the connecting shaft portion (23c), and is integrally connected to the metal pin (23). An allowable portion (spherical curved surface (23a1)) is formed on at least one axial end portion of the support shaft portion (23a) of the metal pin (23), and is configured to increase an amount of swing of the metal lever (21) on the metal pin (23) in the axial direction of the metal pin. Thus in the structure for connecting the metal lever (outside open lever (21)) and the metal link (open link (22)) to each other, improvement in mountability can be achieved.