To provide a whey fermented drink with low viscosity, excellent in stability (precipitation prevention) during long term preservation and palate feeling without using hydrocolloid such as pectin as a conventional stabilizer, and to provide a method for producing the whey fermented drink.

This whey fermented drink contains 0.1-0.3 mass% of lactoferrin as a precipitation preventing agent. The method for producing the whey fermented drink includes fermenting a raw material containing whey protein with lactic acid bacteria followed by adding lactoferrin as a precipitation preventing agent. The amount of lactoferrin added to the whey fermented drink is 0.1-0.3 mass%.