PROBLEM TO BE SOLVED: To provide a raw material capable of effectively masking a food product having a unique flavor such as a beverage product produced by using a separated soybean protein, and to provide a protein beverage using the raw material.SOLUTION: The masking agent capable of improving a unique flavor (taste) included in a protein is obtained by using a dried sugar heated product powder in which a maltose is included as a main sugar. The sugar heated product powder has preferably an L value of a 1 wt.% solution of 10 or larger. The protein beverage is preferably a soybean protein beverage, and pH is preferably 3.0-5.5.
