To provide a compound useful as a MT1 and/or MT2 receptor agonist. The present inventors have studied on MT1 and/or MT2 receptor agonists, and have confirmed that indole compounds have the activity. As a result, the present invention is accomplished. That is, the present invention has a MT1 and/or MT2 receptor agonistic activity and has a low ability of migrating into the central nervous system. Therefore, the compound or a salt thereof can be used as a peripheral MT1 and/or MT2 receptor agonist, and therefore can be used as a therapeutic and/or prophylactic agent for urinary incontinence, particularly stress urinary incontinence and mixed urinary incontinence.本發明為提供一種作為MT1及/或MT2受體激動劑有用之化合物。更詳係為本發明者們對於MT1及/或MT2受體激動劑進行檢討後，確認到吲哚化合物具有該作用而完成本發明。即，本發明之吲哚化合物具有MT1及/或MT2受體激動作用，且中樞移行性低，故作為末梢性MT1及/或MT2受體激動劑可使用於作為尿失禁，特別為腹壓性尿失禁及混合型尿失禁之治療及/或預防劑上。
