PURPOSE: To uniformly enhance the purifying effect of a catalyst by sandwiching an electric heater between the first and second catalysts in a hermetically sealed state in the catalyst device provided to the exhaust air passage of a cooker.

CONSTITUTION: An exhaust air passage 6 is connected to the heating chamber 5 of a cooker main body 1 and a catalyst device 7 is built in the exhaust air passage 6 in a freely detachable manner. The catalyst device 7 consists of a meandering electric heater 8 and the first and second oxidizing catalysts 10, 11 heated by the electric heater 8 and having a large number of gas passing small holes 9,9..., and these catalyst 10, 11 grasp the electric heater 8. Since the electric heater 8 heats the first and second oxidizing catalysts 10, 11 to predetermined decomposition temp. rapidly and uniformly, the purifying effect of the catalysts 10, 11 is uniformly enhanced, and the gas discharged from the heating chamber 5 is uniformly purified when it passes through the small holes 9 of the catalysts 10, 11. Since the electric heater 8 is hermetically sealed and not exposed to gas to be purified, the electric heater is hardly deteriorated.