The purpose of the present invention is to provide a taste-improving agent capable of ameliorating the unpleasant taste of potassium such as harshness, irritativeness and bitterness without reducing the saltiness of potassium-containing foods and drinks. The taste-improving agent for potassium-containing foods and drinks is characterized by comprising a lactic acid-fermented yeast extract which is obtained by fermenting a yeast extract with a lactic acid bacterium and contains 7.5 (w/w)% or more of lactic acid relative to the solid matter of the yeast extract.
