NOVELTY - The apparatus has a methane fermentation tank (1) that performs anaerobic fermentation of fermentation stock solution (7) from water-containing organic waste, and an injection pipe that is connected to the front end side of circulation piping (8), and is arranged so that injection opening of injection pipe faces the downward opening of inner side of baffle plate, or an outer side. The rotational flow is produced on both sides of baffle plate, when biogas injects the to-be-processed liquid by which suction mixing is performed from injection opening.    USE - Methane fermentation apparatus for methane fermentation of fermentation stock solution from water-containing organic waste from high concentration organic wastewater at foodstuff factory, food material residue, home, restaurant, convenience store, livestock excrement from stock raising industry, and water purification plant.    ADVANTAGE - The methane fermentation apparatus has simple structure, the mechanical mechanism for stirring is eliminated, and stirring efficiency is improved. The digestibility is improved. The methane formation efficiency is improved. The methane ratio of biogas is improved and the quality of biogas is improved. The obstruction in sending opening is reduced easily. The generation of floc is prevented, while suspension solid content in fermentation stock solution is refined by cycle flow by performing suction mixing of the biogas. The fermentation efficiency is improved.    DETAILED DESCRIPTION - A water-sealed gas-holder (10) stores the biogas from methane fermentation tank without de-sulfurizing deed or desulfurization by a desulfurization tower. The methane fermentation tank has circulation piping that circulates contact floor and to-be-processed liquid with which the inner side of a vertical baffle plate and baffle plate and outer side is filled. The circulation piping has a circulation pump (6) and an ejector (9) in the circulation direction. The ejector is connected with the gasholder so that suction of biogas is possible. The multiple flat net tubes are arranged in parallel in contact floor that is formed with a plate-shaped contact floor element that is connected with upper end fluctuatably. The middle height position of desulfurization tower (17) is filled with a microorganism carrier (19), a liquid storage element (20) that is provided under microorganism carrier, and a shower pipe (27). A base is connected to the liquid storage element of the desulfurization tower, and a tip is connected to the shower pipe by liquid circulation piping. The introduction of biogas is enabled in the directly under height position of microorganism carrier. The introduction of the digestive liquid from methane fermentation tank of desulfurization tower is enabled at the liquid storage element. The microorganism carrier is formed with a filling portion of synthetic resin flat reticulated cylinder which has flexibility to which flatness is changed with hydraulic pressure. An INDEPENDENT CLAIM is included for a processing method of water-containing organic waste (32) involves grinding by a secondary crushing machine (33) and generating biogas by methane fermentation as fermentation stock solution when remaining in the solid state or slurry is not formed for water-containing organic waste in the case of liquid state or slurry is included. The digestive liquid of desulfurization generated from the desulfurization tower is introduced into an aerobe processing tank (43), while performing methane fermentation using the methane fermentation apparatus. The purified concentration of contamination is discharged to a river through a sedimentation tank (51).    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of the methane fermentation apparatus. (Drawing includes non-English language text)    Methane fermentation tank (1)    Circulation pump (6)    Fermentation stock solution (7)    Circulation piping (8)    Ejector (9)    Water-sealed gas-holder (10)    Desulfurization tower (17)    Microorganism carrier (19)    Liquid storage element (20)    Shower pipe (27)    Water-containing organic waste (32)    Secondary crushing machine (33)    Aerobe processing tank (43)    Sedimentation tank (51)