PROBLEM TO BE SOLVED: To provide an emulsifier for oil-in-water type emulsified fats which is originated from a natural material and is usable in wide applications.SOLUTION: A method of producing an emulsifier for oil-in-water type emulsified fats is characterized by subjecting an ingredient (A) to a treatment (B). (A): an aqueous solution comprising a milk-originated phospholipid and a milk protein, in a content of the milk protein of 1-15 pts. mass to one pt. mass of the milk-originated phospholipid. (B) addition of a calcium salt in an amount of 0.01-1 pt. mass to one pt. mass of the content of the phospholipid (A).