PURPOSE: To easily obtain milk having low phosphorus content and suitable as a drink for aged person, by coagulating and separating casein from milk, precipitating phosphoric acid in the remaining milk whey as Ca salt, adding the separated casein to the whey and emulsifying the mixture.

CONSTITUTION: Milk is added with an acid and/or rennet and coagulated casein is separated. The remaining milk whey is added with a calcium salt (e.g. calcium chloride) to precipitate free phosphoric acid in the whey in the form of calcium phosphate having low solubility. The solution produced by removing the precipitate is added with the casein separated in the first step to obtain a mixture containing 1W2g of phosphorus per 100g of protein. The objective milk having low phosphorus content is produced by emulsifying the mixture. Only the phosphorus component in milk can be selectively decreased to enable the preparation of low-phosphorus milk without decreasing the contents of other nutrient components.