To provide an ammonia cleaning catalyst capable of further reducing production of nitrogen oxide, more efficiently oxidation-decomposing ammonia to nitrogen and water and more efficiently cleaning ammonia, an ammonia cleaning method using the catalyst and an ammonia cleaning catalyst apparatus provided with the catalyst.

The catalyst has a first composite body containing a noble metal and a heat-resistant oxide as active ingredients; and a second composite body containing a transition metal or a rare earth metal and any one oxide selected from titania, zirconia, silica and alumina as active ingredients. The first composite body and the second composite body use the catalyst having different composition. Thereby, ammonia can be efficiently cleaned.

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