A thermal decomposition furnace for exhaust gas to thermally decompose harmful substances contained in the exhaust gas to render them harmless. The thermal decomposition furnace includes a heating chamber for heating the exhaust gas; an inlet port for introducing the exhaust gas into the heating chamber; at least one pair of electrodes provided within the heating chamber; a plurality of light emitting heaters which contain carbon as a main ingredient; and an outlet port for discharging the thermally decomposed exhaust gas. The plurality of light emitting heaters are placed in an oxygenless or a vacuum environment.
