To reduce assembling man-hours and to reduce costs by integrally molding a composite material wing by using a hollow molded product made of a light and highly rigid material usable as a fuel tank as a laminating jig.

The framed structure 10 including front and rear beams 11, 12 and a rib 13 is molded by integrally molding a fiber reinforced resin composite material by using a laminating method. Laminating jigs 14, 15 are molded by performing blow molding by a light and highly rigid thermoplastic material. The laminating jig 15 is fixed to the front and rear beams 11, 12 and the rib 13 and the laminating jig 14 is fixed to the front beam 11 and the rib 13. As a result, a wing type laminating jig of a composite material is molded. On an outside face of the wing type laminating jig, prepreg 19 constituting upper and lower outer plates of a main wing structure is laminated. The laminated prepreg 19 is pressurized, heated and hardened together with the wing type laminating jig. Thus, the main wing structure into which the laminating jigs 14, 15 are integrally incorporated is molded.