To provide an inexpensive and effective method and apparatus for desulfurizing biogas.

In the method for desulfurizing the biogas, the biogas generated by the anaerobic treatment of organic matter is brought into contact with an aqueous solution containing a reducing agent or the reducing agent and polyhydric alcohol to absorb hydrogen sulfide in the biogas by the aqueous solution. The apparatus for desulfurizing the biogas is equipped with a device for bringing the biogas into contact with the aqueous solution to absorb hydrogen sulfide in the biogas by the aqueous solution, Further, in the method for desulfurizing the biogas, the biogas desulfurized by the reducing agent is brought into contact with an aerobic microorganism suspension and the microorganism suspension after the contact with the biogass is aerobically kept.