PROBLEM TO BE SOLVED: To provide a production method of a fermented product which uses a natural fermentation system, the fermented product and a method of expanding and utilizing the bacterial flora.SOLUTION: A production method of a fermented product comprises includes a preservation process of putting a raw material in a stopper-executable container, closing the opening with a plug and preserving, in a semi-closed system in a container-paced state, under controlled specified low-temperature conditions for a specified period. In the preservation process, a specified bacterial flora is formed by utilizing a natural fermentation system based on natural fermentation by self-growing microorganisms and sugar originated from the raw material and subjected to a treatment of removing impurities so as to obtain a fermented product containing the specified bacterial flora and achieving non-detection of various germs (10,000 bacteria/g or lower) without heating. There are also provided the fermented product and a method of expanding and utilizing the bacterial flora. According to these, a fermented product which is useful as a base material for food production can be produced and provided.
