The present invention provides a lactic acid bacterial fermentation-promoting agent and a fermentation method suitable for use in food production. The present invention relates to a fermentation promoting agent for a lactic acid bacterium, having a compound having a purine skeleton with a hydrogen atom attached to the carbon atom at position 2, and a method for promoting fermentation for a lactic acid bacterium using the same and a method for producing a fermented food such as fermented milk.
