The present invention molds a tube that is difficult to bend and has a small outer diameter by means of an easy step. The present invention has: a primary molding step for molding a primary molded body by means of performing resin molding having disposed a reinforcing member and core pin (4) in the cavity of a first die formed from a bottom mold (30) and top mold (40) for primary molding； and a secondary molding step for covering the reinforcing member by means of performing resin molding having disposed the primary molded body in the cavity of a second die having a larger internal diameter than that of the abovementioned cavity.藉由簡易製程成形出外徑小且難以折彎之管。包含：一次成形步驟，藉由在以一次成形用之下模(30)與上模(40)成形之第1模具之空腔配置補強構件與中子銷(4)並進行樹脂成形，以成形出一次成形體；以及二次成形步驟，藉由在具有較上述空腔之內徑大之內徑之第2模具之空腔配置一次成形體並進行樹脂成形，以被覆補強構件。
