A movable mold and a slide mold are employed. There is also employed a deposition apparatus which is equipped with a deposition element such as a target electrode in the inside of a depositing chamber. A body portion and a cover member are primarily molded by the movable mold and the slide mold. The molds are opened while the body portion being left in the movable mold and while cover member being left in slide mold. The body portion left in the movable mold is deposited in the molds with its inner surface being covered with the depositing chamber. Next, the slide mold is driven so that the cover member may be registered with the deposited body portion. Then, a secondary molding resin is injected to integrate the body portion and the cover member.