To obtain a beverage containing milk whey protein free from gelation, coagulation, precipitation, etc., excellent in flavor, pleasantly drinkable property, storage stability by heat sterilizing the liquid composition containing milk whey protein after acting transgluta-minase.

This milk whey protein-containing beverage is obtained by acting 5-50 units (per 1gr of protein in the liquid composition) of transgluta minase to the liquid composition containing milk whey protein, then adding gustatory substance such as fruits juice, sweetening, acidulant, flavor, etc., and heat sterilizing. Preferably this beverage has ≥6.2 or ≤3.6pH.