In view of the above-discussed state of the art, it is an object of the present invention to provide a method of adhesion of conductive materials which uses a water-based ecofriendly adhesive and can give uniform adhesive layers capable of leading to constant and high levels of adhesion strength and excellent in insulating properties even in the case of molded articles and the like. A method of adhesion of conductive materials comprising the step (1) of forming an adhesive surface having an adhesive resin layer on a conductive material by an electrodeposition step with an adhesive composition and the step (2) of joining an adherend surface of an adhesion target to the adhesive surface having the adhesive resin layer obtained in the step (1), wherein the adhesive composition comprises a hydratable functional group- and unsaturated bond-containing cationic resin composition.