To provide a heat radiation reflecting furnace efficiently using radiation energy being sealed in the furnace as much as possible while avoiding or reducing heat storage in components of the furnace and suppressing radiation energy loss with exhaust gas, and sufficiently serving for practical use while securing high-temperature reliability.

A first gap 21 as an air heat insulating layer is provided between a heat resistant tube 2 having a metal film formed on the inner face and a first inner tube (a silica tube) 3, and a second gap 22 is provided between the first inner tube 3 and a second inner tube (a process tube) 4. A heater 5 is arranged in the second gap 22. A water cooled jacket 1 encircles the outer face of the heat resistant tube 2, and a third gap 23 as a refrigerant ventilating passage is provided therebetween. The heat resistant tube 2 is cooled through its outer face by the water cooled jacket 1. As a result, heat to be radiated from the whole furnace to the outside is cooled.