Study was made on the storage method of a methane component in biogas mainly composed of CO2 and methane gases. Methane clathrate as molecular complex is one kind of clathrate compounds. Eight methane gas molecules are absorbed into 46 water molecules, or methane gas of 216 l is absorbed into water of 1 l, resulting in considerable compact methane storage. Although methane clathrate is usually stable only under a condition of low temperature and high pressure, its formation equilibrium shifts toward a low pressure/high temperature side by adding additives such as amine, ether and ketone. Acetone can shift formation pressure from 30 to 10atm at 1degC, and formation temperature from 1 to 10degC at 30atm. Although methane liquefaction is also an efficient storage method, it requires liquefaction temperature and pressure of -83degC and 45.6atm, respectively. The distance between methane molecules in clathrate lattice can be more shortened than that in high- pressure charged gas, suggesting higher storage efficiency. The study result showed that the handling of methane clathrate is possible around room temperature and pressure. 7 refs., 5 figs.