PURPOSE: To easily remove org. materials without requiring replacement and secondary treatment by continuously treating a gas contg. org. materials with a reaction vessel and an adsorption tower by the use of slurrylike activated sludge.

CONSTITUTION: A gas contg. org. materials is exhausted via a duct 9 from air diffuser pipes 2 in the form of fine bubbles into a reaction vessel 1 contg. slurrylike activated sludge 3, where org. materials are allowed to settle together with bacteria by the oxidation effect of the activated sludge 3 and are removed by about 93%. The activated sludge in the tank 1 is about 5,000W8,000ppm, and the thickness thereof is kept at about ≥2.5m. Thence, the gas flows toward an adsorption tower 4. In the tower 4, an adsorption layer 51 consisting of corrosion resistant filter media 5 having good adhesivity to organisms is provided, and the slurrylike activated sludge 3 sucked up by a slurry pump P is injected through a pipe 11 to the layer 51 from shower sprays 6. Here the gas contg. org. materials is removed of the org. materials, whereby about ≥98% the org. materials of the entire part of the gas are removed. The purified gas is exhausted through an exhaust port 12.