To provide an apparatus for decomposing and eliminating chemical pollutants (odors) in exhaust air exhausted from each business place, for inactivating, decomposing and eliminating germs such as bacteria in a building, for example inside a room, of each business place, and for decomposing and eliminating malodorous components more effectively in a simpler device.

The apparatus, which is equipped with an ultraviolet irradiation device 7 in a reaction tower where a gas to be treated is introduced from the lower part and made to rise to the upper part, and is brought into contact with circulating purified water falling from the upper part in an opposing manner, is used as the apparatus for decomposing and eliminating the chemical pollutants, the specific malodorous components and bacteria.