An ammonia oxidation catalyst being superior in heat resistance and capable of suppressing by-production of N2O or NOx. The ammonia oxidation catalyst is made by coating at least two catalyst layers having a catalyst layer (lower layer) including a catalyst supported a noble metal on an inorganic base material including any of a composite oxide (A) having at least titania and silica as main components, alumina, and a composite oxide (B) consisting of alumina and silica; and a catalyst layer (upper layer) including a composite oxide (C) consisting of at least silica, tungsten oxide, ceria and zirconia, at the surface of an integral structure-type substrate, wherein a composition of the composite oxide (C) is silica: 20% by weight or less, tungsten oxide: 1 to 50% by weight, ceria: 1 to 60% by weight, and zirconia: 30 to 90% by weight.