An autoclave (1) is one in which a heat application target molded material (W) is retained in shape by a retaining jig (4) which has a cavity (15) therein, and is heat-cured with high temperature gas. The autoclave is provided with: a pressure vessel (2) in the interior of which the molded material (W) is arranged; a high temperature gas supplying device (5) which supplies the high temperature gas to the molded material (W) within the pressure vessel (2); and an auxiliary high temperature gas supplying device (7) which supplies the high temperature gas into the interior of the cavity (15).