The invention discloses an ammonia oxidation catalyst being superior in heat resistance and capable of suppressing by-production of N 2 O or NO x , and leakage of ammonia, by spray supplying urea water or the like to a selective catalytic reduction, in purification of nitrogen oxides discharged from a boiler or the like; and an exhaust gas purification apparatus and an exhaust gas purification method using the same. It is provided by an ammonia oxidation catalyst (AMOX) or the like for oxidizing and removing surplus ammonia, in selectively reducing nitrogen oxides by adding urea or ammonia and using a selective catalytic reduction (SCR) catalyst, into exhaust gas, wherein 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 a
