PURPOSE: A sucking-type cultivation tank is used to prevent the structure from becoming too large and a natural culture medium containing saccharified rice bran and phosphatidylcholine is used to enable the yeast to be used in the production of food or beverage products directly.

CONSTITUTION: KOJI essence or saccharified rice bran is combined with phosphatidylcholine and the resultant culture medium and a yeast are charged in a cultivation tank 1, then the tank is tightly closed. The air in the tank is evacuated by the suction mechanism 9 and sterilized air is fed from the air feeder 6 into the culture mixture V in the tank. This condition is continued to effect yeast cultivation. Resultantly, a large scale installation becomes unnecessary and the air introduction is improved. Further, it becomes unnecessary to remove synthetic substances by centrifugation and the yeast can be safely used directly as an alcohol source in the production of food or beverage products.