PURPOSE: To make effective deodorizing treatment with a compact structure by providing a deodorizing catalyst placed on the downstream side of an ozonator and for adsorbing odorous components and also for accelerating the reaction between the odorous components and ozone, and an ozone decomposing catalyst placed on the downstream side of the deodorizing catalyst and for decomposing unreacted ozone.

CONSTITUTION: While odorous air is passed through an air current flow passage 11 of a deodorizing catalyst 1A, the odorous components are adsorbed and collected by active carbon constituting its passage wall, and at the same time, ozone O3 flowing in the air current flow passage 11 effectively acts on the collected odorous components to oxidize and decompose them. Since, to completely decompose and remove the odorous components, plenty of O3 is fed, excess O3 passed through the air current flow passage 11 of the deodorizing catalyst 1A as it is without reacting with the odorous components is caused. Therefore, an ozone decomposing catalyst 1B is installed in a position on the downstream side of the deodorizing catalyst 1A. When the excess ozone is caused to flow in the air current flow passage 11, it is oxidized and decomposed by a catalytic material mainly consisting of titanium and silica constituting the passage wall to turn it into harmless oxygen.