An object of the present invention is to provide a fermented product containing equol-producing microorganisms in the state of living cells by which equol production ability is maintained. When producing a fermented material by using an (equol-producing microorganism, with soybean powder or soybean milk as raw materials, (1) preparing a mother starter by fermentation under anaerobic conditions by using an equol-producing microorganism in the presence of a daidzein species at pH 5.0 or higher, (2) preparing a bulk starter by fermentation under anaerobic conditions by using said mother starter in the presence of a daidzein species at pit 5.0 or higher, and (3) preparing a fermented material by fermentation by using said bulk starter in a medium containing soybean powder or soybean milk, enables production of a fermented material containing microorganisms in the state of living cells in which the equol production ability is maintained.本發明之目的在於提供一種於活菌狀態下含有產生雌馬酚之微生物的發酵製品，且維持該產生雌馬酚之微生物的雌馬酚產生能力。使用產生雌馬酚之微生物並以大豆粉末或豆乳作為原料製造發酵物時，可藉由下述步驟來製造活菌狀態下含有維持雌馬酚產生能力之微生物的發酵物：(1)使用產生雌馬酚之微生物，在木質素黃酮(daidzein)類存在下，於pH5.0以上且厭氧條件下進行發酵以調製菌元(mother starter)；(2)使用前述菌元，在木質素黃酮類存在下，以pH5.0以上進行發酵，藉以調製大量菌元(bulk starter)；及(3)使用前述大量菌元，在含有大豆粉末或豆乳之培養基中進行發酵以調製發酵物。
