To enhance a junction strength to a resin material by only formation treatment of a coating film layer of triazine dithiol derivative, irrespective of a kind of a metal material, and to enhance a manufacturing efficiency.

This insert molding S is joined by insert-molding the resin material R, to the metal material M formed with the coating film layer F of triazine dithiol derivative on a surface, and the metal material M is constituted of a sintered body manufactured by a metal injection molding method. The metal injection molding method is called as a so-called MIM (metal injection molding) method, and is a method of adding a binding material of imparting flowability such as a resin and wax to metal powder, of imparting plasticity by heating/kneading, to be injection-molded as same as a plastic, and of obtaining the desired sintered body thereafter by defatting and sintering.