The present invention provides a lactic acid bacterial fermentation-promoting agent suitable for use in food production. The present invention relates to a fermentation promoting agent for Streptococcus thermophilus, comprising a solution prepared by exposing an alkaline solution comprising a reducing sugar to a temperature in the range of 5° C. or more and 135° C. or less to induce a color reaction of sugar, and a production method thereof； and a method for promoting fermentation for Streptococcus thermophilus using the fermentation promoting agent and a method for producing a fermented food such as fermented milk.
