DENITRIFICATION DEVICE

PROBLEM TO BE SOLVED: To enable the oxidation of SO2 contained in an exhaust gas into SO3 to be inhibited by applying a substance which diminishes the oxidation properties of a metallic oxide sticking to a denitrification catalyst to the upstream side part of the denitrification catalyst. SOLUTION: As illustrated on the illustration, i.e., the expanded lateral view sketch of part 4 of a denitrification catalyst, a substance which inhibits the oxidation properties of a metallic oxide such as vanadium oxide sticking to the denitirication catalyst, for example, an oxide of silica(Si), molybdenum(Mo) or arsenic(As) or carbon is coated on the surface of the upstream side part 4a of the denitrification catalyst. In addition, the length(Y) of the upstream side part 4a on which the metallic oxide of silica or molybdenum or carbon is coated is set to be 1/2 or less of the length (X) of the whole denitrification catalyst (i.e., 4) (i.e., constituted to be Y