An electric generating system by gasification generates fuel gas from material such as organic wastes and generates electricity by utilizing fuel gas in a fuel cell. The electric generating system comprises a gasification process (1, 2) for gasifying the material to produce gas, a gas purifying process for purifying the gas produced in the gasification process, a gas pressurizing process as a part of the gas purifying process for pressurizing the produced gas, and a hydrogen purifying process as a part of the gas purifying process for purifying hydrogen by hydrogen absorbing alloy.