A taste improving agent containing as an active ingredient a whey mineral satisfying all the criteria (a), (b), (c), (d), and (e) below: (a) an ash content in an solid portion of the whey mineral is 25 to 75% by mass; (b) a calcium content in a solid portion of the whey mineral is less than 2% by mass; (c) a calcium content in an ash portion of the whey mineral is less than 5% by mass; (d) a lactic acid content in a solid portion of the whey mineral is 1.0% by mass or more; and (e) a pH of an aqueous solution containing 0.1% by mass of a solid portion of the whey mineral is 6.0 to 7.5.