The present invention molds, with simple processes, a tube which has a smaller outer diameter and is hardly bent in a folded manner. The present invention includes (i) a primary molding step of forming a primary molded body by carrying out resin molding while a reinforcing member and a core pin (4) are placed in a cavity of a first mold made up of a lower mold (30) and an upper mold (40) for primary molding and (ii) a secondary molding step of covering the reinforcing member by carrying out resin molding while the primary molded body is placed in a cavity of a second mold that has an inner diameter larger than an inner diameter of the cavity of the first mold.