To improve a strength of a periphery such as a cutout periphery or the like in a composite structure having a high strength periphery (here, the periphery is a periphery of a part which needs reinforcing, and hereinafter, the same) and to lighten its weight by eliminating a necessity of reinforcing of a doubler or the like.

A composite structure 10 comprises the cutout periphery 11 formed thereat. The composite structure is completed by repeatedly pressurizing a fiber structure of a woven fabric or the like before an overall circumference of the periphery is impregnated with a resin between a width W1, raising a density of the woven fabric, and thereafter impregnating the fabric with the resin. Thus, a strength of the periphery is improved, reinforcing is not required, and its weight can be lightened. Further, a working step of increasing a thickness of a plate is eliminated to reduce its manufacturing cost.