PURPOSE: To efficiently remove the component of malodorous gas to be treated by heating a catalyst by a microwave absorbing material absorbing a microwave to be heated to required temp. to activate the same and removing the malodorous component generated from an object to be heated.

CONSTITUTION: A microwave absorbing material 18 (e.g.; silicon carbide plate) absorbing a microwave to be heated to required temp. and the catalyst 17 heated by the microwave absorbing material 18 raised in its temp. to be activated and removing the component generated from the object to be treated received in the heating chamber 2 are provided in the heating chamber 2. As a result, when the object to be heated is irradiated with a microwave, the absorbing material 18 absorbs the microwave to be heated rapidly and the catalyst 17 can be rapidly and uniformly heated by the absorbing material 18 raised in its temp. Therefore, the catalyst is sufficiently activated immediately after starting the irradiation with a microwave to be able to develope catalytic function and the component to be treated such as malodorous gas generated from the object to be heated can be efficiently removed without being leaked out of the heating chamber.