Abstract: Vulcanization apparatus to vulcanize, with the heat and pressure of a fluid, a molding of rubber belt material (before being cut crosswise into the final products) while the molding is being held intact over the external circumference of a hollow cylindrical mold. A steaming jacket is provided into which the mold with the molding sticking intact thereto is inserted. The steaming jacket comprises a rubber sleeve on the interior of a cylindrical casing and secured and sealed at upper and lower axial ends of the rubber sleeve against the casing. The sleeve is swelled inwardly when heated high pressure fluid is passed through an internal space between the casing and the sleeve. The vulcanization apparatus is provided with steam supply and discharge pipes for the internal space of the jacket and steam supply and discharge pipes for the mold inserted into the jacket.