PROBLEM TO BE SOLVED: To solve at least one among problems that the excessive sourness of a malt beverage using malt having a high phosphoric acid ion feed source content is reduced or relaxed, that the deepness of the beverage is increased and that the bitterness as the aftertaste of the beverage is reduced.SOLUTION: The proteolysis (KI) of malt in which the amount of a phosphoric acid ions feed source is high is controlled within a specified range.