The present invention relates to improvement of the unpleasant taste characteristic of potassium salts without adversely affecting the salty taste of the potassium salts and provides a method for reducing sodium contents in foods and drinks without reducing salty taste of the foods and drinks and also provides sodium-reduced foods and drinks. The present invention relates to a taste-improving agent for a potassium salt or a potassium salt-containing food or drink, and the agent contains a phthalide as an active ingredient.
