Culture method and culture apparatus of microorganisms

The gas-assimilating microorganism, regardless of variations in the supply flow rate of the substrate gases, are stably cultured. In cultures 2 of the culture tank 10 for culturing gas assimilating microorganisms 3. Substrate gas containing CO and H When the supply flow rate to the culture tank 10 of the substrate gases or the predetermined component is equal to or less than a predetermined value, rapidly discharging the culture solution 2a from the culture tank 10.