NOVELTY - The fermentor for fermentation gas production by biological decomposition of substrate containing organic material, comprises a lengthwise-extending closed container (1) with an inlet opening (26) for the substrate and outlet openings (19, 20) for the decomposition products. The container exhibits reaction volume cells (2), which contain a stirrer (3) for mixing the substrate. The inlet opening is intended for the substrate distributed into the container, is arranged in overlapping- or tangential area of neighbouring stirrers and is connected via lines with a common supply for the substrate.    USE - For fermentation gas production by biological decomposition of substrate containing organic material.    ADVANTAGE - The fermentor is simple and economic, avoids overloading of anaerobic biocenosis in the input opening and ensures stable decomposition of substrate.    DETAILED DESCRIPTION - The fermentor for fermentation gas production by biological decomposition of substrate containing organic material, comprises a lengthwise-extending closed container (1) with an inlet opening (26) for the substrate and outlet openings (19, 20) for the decomposition products. The container exhibits reaction volume cells (2), which contain a stirrer (3) for mixing the substrate. The inlet opening is intended for the substrate distributed into the container, is arranged in overlapping- or tangential area of neighbouring stirrers and is connected via lines with a common supply for the substrate. A dosing device is assigned to each inlet opening and is connected with a central control unit. In transmission or tangential area of the stirrers, flow-diverting elements are intended crosswise to the longitudinal extending of the container.    An INDEPENDENT CLAIM is included for procedure for production of fermentation gas by biological decomposition of substrate containing organic material.    DESCRIPTION OF DRAWING(S) - The diagram shows the fermentor with several reaction volume cells;    Container; (1)    Reaction volume cells; (2)    Stirrer; (3)    Outlet opening; (19, 20)    Inlet opening. (26)