NOVELTY - Producing biogas involves taking raw material for fermentation and pouring into the feedstock tube. The blocking plate is provided between the annular pipe and side wall of the discharging pipe to form a fermentation area for producing marsh gas. The marsh liquid is pushed adjacent to the fermentation area, and the feedstock tube and discharging tube are prepared for the process. The marsh gas generated by adjacent area flows continuously when the fermented biogas becomes thick provided each area of the fermentation system is mutually connected.    USE - Method for producing biogas (claimed).    DETAILED DESCRIPTION - Producing biogas involves taking raw material for fermentation and pouring into the feedstock tube. The blocking plate is provided between the annular pipe and side wall of the discharging pipe to form a fermentation area for producing marsh gas. The marsh liquid is pushed adjacent to the fermentation area, and the feedstock tube and discharging tube are prepared for the process. The marsh gas generated by adjacent area flows continuously when the fermented biogas becomes thick provided each area of the fermentation system is mutually connected. The annular pipe of biogas fermentation liquid feedstock tube or discharge tube reaches to the lowest position of the side wall and the continuously generated biogas overflows from sides of the system. The inner annular pipe is used for fermentation of marsh gas. The biogas liquid level of feedstock pipe and discharge pipe is raised which then flows with water pressure in the discharge tube by way of drain pipe. The top part of gas-guide tube and fermentation area are used to provide input to marsh gas. The marsh gas and space in the fermentation cell is reduced. The cell adjacent to the fermentation cell is used for fermentation of biogas. The hydraulic liquid is transported and stored through feedstock drain pipe provided with one-way flow into the feedstock tube. The complementary annular fermentation pipe with one-way flow reduces the gas space using the rest of fermentation area and marsh gas is stored.