The biogas generator comprises a vessel for the raw material with a comminutor and homogeniser, fine comminution disintegrator, preheater, biogas generator with processing pipes (9,10,23,24,26) and agitator (21), stirrer (11) and fermented material vessel (2). The biogas generator has transverse partitions (1) dividing vessel (2) into chambers of acid (3), regressive acid (4) and alkaline (5) fermentation respectively, and filters (6) of flexible fibres fastened in the upper part (7) of chambers (3,4,5) and forming with partitions (1) a sedimentation section (8) having pipe connections (9) for the discharge of slurry in the lower section, and pipe connections (10) for clarified mash in the middle section, and transferrer (11) of floating fraction in the upper section. The biogas generator has subchambers (12,13,14), for methane fermentation, biogas treatment and clarified mash respectively, made from sections (15) with spargers (16) in them. There is a granular charge (17) for immobilising microorganisms - degraders, and overflow pipes (18).    USE -   The generator is used in establishments of the agroindustrial complex for generating biogas and protein vitamin additives from materials resulting from the vital activities of animals and poultry.    ADVANTAGE -   The device increases the effectiveness of biogas prodn., i.e., the yield of biogas from 1 kg of ashless organic matter is increased from 0.6-0.8 kg to 1.3-1.5 kg, increases the methane content in the biogas to 95-98% and its calorific value. The breakdown of ashless organic matter is increased from 5-50% to 90-95%, shortens the duration of the fermentation, creates conditions for transfer of the operation of sewage works of the agro-industrial complex to profitable conditions of operation. Use of the protein-vitamin additive reduces the usual food requirement by 20-30%, increases the egg and milk yields. Meat wt. increases by 30-40%. Reduces epizootic disease in young stock. Improves the genetics of the parent gps. of animals and birds.