A composite structural body includes a base material; and a film-like structural body formed on a surface of the base material by causing an aerosol to impinge on the base material. The aerosol contains fine particles dispersed in a gas, and a distance between an end part of the film-like structural body and an outermost part closest to the end part of a portion of the film-like structural body has a film thickness equal to an average film thickness of the film-like structural body as viewed perpendicular to the surface being 10 times or more of the average film thickness.