To enhance the absorption amt. of NOX by the irradiation effect of light having a wavelength within an ultraviolet region by combining a light source emitting light having a wavelength within the ultraviolet region and a catalyst capable of absorbing nitrogen oxide.

An NOX purifying apparatus has a combination of a light source capable of emitting light having a wavelength within an ultraviolet region with a catalyst capable of absorbing nitrogen oxides in an oxidizing atmosphere and a reducing atmosphere, especially, a composite oxide catalyst having a perovsite structure or a laminar perovskite structure. As a result, as compared with a case using only a usual NOX absorbing catalyst, NOX absorbing quantity can be enhanced by the irradiation effect of light having a wavelength with in the ultraviolet region and, since the discharge of NOX within a temp. region of 300°C or higher is suppressed, NOX can be effectively absorbed. As the light source emitting light having a wavelength within the ultraviolet region, a halogen lamp can be used and the NOX purifying apparatus can be easily constituted by the combination of the light source with the composite oxide catalyst.