NOVELTY - Compost fermentation processing system comprises an exhaust system that divides into a zone that always exhausts the odor gas from interior of compost fermentation building (30), and zone that exhausts only when the level of odor gas exceeds the predetermined value, and exhausts the odor of the compost (2) of each zone. The zone that always exhausts the odor gas is a zone that passes compost in predetermined period from compost injection by stirring apparatus (3).    USE - For performing fermentation processing of compost such as livestock dung and foodstuffs residue.    ADVANTAGE - The exhaustion of odor gas is completely performed even if the whole compost fermenter is not covered by the hood. The size and cost of the exhausting apparatus can be reduced.    DETAILED DESCRIPTION - Compost fermentation processing system comprises an exhaust system that divides into a zone that always exhausts the odor gas from interior of compost fermentation building (30), and zone that exhausts only when the level of odor gas exceeds the predetermined value, and exhausts the odor of the compost (2) of each zone. The zone that always exhausts the odor gas is a zone that passes compost in predetermined period from compost injection by stirring apparatus (3). An air circulation prevention unit (20a) prevents free ventilation between the zones. The zone has a position sensor (7) to detect the position of stirring apparatus and exhausts the odor of compost of compost fermentation building based on position detection result. A controller switches the exhaust system in the zone. An odor detector (6) detects the odor of the chamber. The controller controls the air flow of the air blower in exhaust system according to level of detected odor.    An INDEPENDENT CLAIM is included for exhaustion method of odor gas.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic diagram of compost fermentation processing system. (Drawing includes non-English language text)    Compost fermenter (1)    Compost (2)    Stirring apparatus (3)    Odor detector (6)    Position sensor (7)    Air circulation prevention unit (20a)    Compost fermentation building (30)    Compost fermentation processing system (50)