PROBLEM TO BE SOLVED: To provide a novel compound, and a pharmaceutically acceptable salt thereof, useful in the treatment or prevention of diseases caused by inhibitory activity on glycine intake, such as schizophrenia, Alzheimer's disease, cognitive impairment, dementia, anxiety disorders (generalized anxiety disorder, panic disorder, obsessive-compulsive disorder, social anxiety disorder, post traumatic stress disorder, specific phobias, acute stress disorder etc.), depression, substance abuse, convulsions, tremors, pain, or sleep disorders.SOLUTION: There is provided a compound represented by formula [I], or a pharmaceutically acceptable salt thereof.【課題】本発明は、グリシン取り込み阻害作用に基づいた統合失調症、アルツハイマー病、認知機能障害、認知症、不安障害（全般性不安障害、パニック障害、強迫性障害、社会不安障害、外傷後ストレス障害、特定の恐怖症、急性ストレス障害等）、うつ病、薬物依存、痙攣、振戦、疼痛、又は睡眠障害等の疾患の予防又は治療に有用な新規な化合物又はその医薬上許容される塩を提供することを目的とする。【解決手段】式［Ｉ］で表される化合物又はその医薬上許容される塩。【選択図】なし
