A compound has an intestinal phosphate transporter (NPT-IIb) inhibitory action and is useful as an active ingredient of an agent for treating hyperphosphatemia, preventing hyperphosphatemia, or both. The compound is a tetrahydrobenzothiophene compound. A pharmaceutical composition for treating hyperphosphatemia includes the compound or salt thereof. A method of treating hyperphosphatemia includes administering to a subject an effective amount of the compound or salt thereof.
