To provide a substrate processing apparatus, comprising: a reaction vessel having a processing chamber inside that processes a substrate; a heating device that heats said substrate from an outer peripheral side of the reaction vessel; a lid member that closes the processing chamber; an attachment/detachment jig placed on the lid member for attaching/detaching the reaction vessel from an inside of the heating device; and a support section provided in an upper side of a lower end of the reaction vessel on an inside wall of the reaction vessel, and abutted on an upper surface of the attachment/detachment jig for attaching/detaching the reaction vessel from the inside of the heating device.