A composite structure includes: a cover plate having a countersunk hole and a plate side fitting hole; a bearing plate having a screw hole and a screw side fitting hole located opposite from the plate side fitting hole through the screw hole; and a plate screw component including a screw part engaged with the screw hole, and a plate side fitting part and a screw side fitting part respectively fitted with the plate side fitting hole and the screw side fitting hole to be in alignment with each other. A difference δϕa in diameter between the plate side fitting hole and the plate side fitting part, a difference δϕb in diameter between the screw side fitting hole and the screw side fitting part, and an effective difference δϕc in diameter between the screw hole and the screw part satisfy a dimensional relation of δϕa