To obtain a milk-containing food, capable of preventing the milk- containing food from deteriorating with time and stabilized in quality.

Kojic acid is added to a milk-containing food such as a fermented milk or a lactic acid bacteria beverage to thereby provide a milk- containing food, capable of preventing the quality from deteriorating with light, heat, air, etc., during the production process, distribution stage and preservation and maintaining a good flavor for a long period and having high and stabilized quality.