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 pH 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.