PURPOSE: To improve the thermal radiation efficiency and give a sterilizing effect by far infrared rays by providing a secondary infrared ray radiation means by means of ceramic coating film which is heated through thermal conductivity by a primary infrared ray radiation means that is heated by a burner part.

CONSTITUTION: An infrared ray radiation means 12 consisting of a metallic tube etc. is disposed above a burner part 11, and a far infrared ray radiation means 13 is disposed above the afore-said. The inside of a heat-resistant retainer tube 13a of the far infrared radiation means 13 is coated with a highly efficient infrared ray absorbing ceramic paint 13b, and its outside is coated with a highly efficient far infrared ray radiation ceramic paint 13c. This heat-resistant inorganic adhesive paint uses alkaline metallic salts or phosphate salt (acid) group. If oxidization is to be prevented, a coating having silicon alkoxide as a primary constituent is applied and fired. An infrared ray reflecting means 14 has a coated film 14b made from fine powders of aluminum or stainless steel on the substrate 14a.