PURPOSE: To obtain an acidic milk beverage, containing alginic acid and capable of withstanding sterilization without causing precipitation of milk proteins with time at all if prepared by using a raw material containing already denatured proteins.

CONSTITUTION: The aimed beverage obtained by adjusting the pH of a mixture solution of alginic acid, a dairy product and an alkaline agent to the isoelectric point or above of milk proteins, reacting the alginic acid with the milk proteins, then adding an acid and subsequently sterilizing the resultant mixture. Furthermore, nonfat solid content of the dairy product in the afore-mentioned beverage is preferably ≥0.04wt.% and the amount of the added alginic acid is preferably ≥0.01wt.% based on the above-mentioned beverage.