The problem to be solved by the invention is to provide a food or a drink containing an acidic protein which has a favorable flavor with relieved astringency characteristic to a protein dissolved under acidic conditions to thereby broaden the flavor variety of protein-containing foods or drinks. The above problem can be solved by adding a water soluble polysaccharide, a water soluble basic salt, an alkali metal salt of an organic acid, a basic monosaccharide, a basic oligosaccharide or the like to a food or a drink containing a protein dissolved under acidic conditions to thereby relieve the astringency originating in the protein dissolved under acidic conditions.