An object of the present invention is to provide a stable deodorizing performance for a long period of time at a low cost even for a odor gas of a complex odor accompanied by fluctuations in odor concentration and odor quality. A biofilter 21 that digests odorous gas G by biological treatment is configured by filling wood chips 21A in a bulk density range of 150 to 500 kg / m 3 , and a sprinkling means 30 is disposed above the biofilter 21. The water content of the wood chip 21A is maintained at 150% or more and 300% or less by watering. Further, the water sprayed by the water spraying means 30 is circulated by collecting the surplus water W 1 that has passed through the biofilter 21 by the circulation means 40 and supplying it to the water spraying means 30. [Selection] Figure 2【課題】臭気濃度や臭気質の変動を伴う複合臭の臭気ガスに対しても、低コストで長期間安定した脱臭性能を発揮できること。【解決手段】臭気ガスＧを生物的処理によって消化するバイオフィルタ２１を、木材チップ２１Ａを嵩密度１５０～５００ｋｇ/ｍ3の範囲内で充填して構成し、散水手段３０によってバイオフィルタ２１の上方からなされる散水により木材チップ２１Ａの含水率を１５０％以上、３００％以下に維持する。また、循環手段４０によりバイオフィルタ２１を通過した余剰水Ｗ1を回収し散水手段３０に供給することで、散水手段３０で散水する水を循環させている。【選択図】図２
