PROBLEM TO BE SOLVED: To provide a compound useful as an agent for treating or preventing stress urinary incontinence, having 5-HT2C receptor operation activity.SOLUTION: The present invention provides an indole derivative represented by the following formula or its pharmaceutically acceptable acid addition salt.SELECTED DRAWING: NoneCOPYRIGHT: (C)2017,JPO&INPIT【課題】5-HT2C受容体作動活性を有する、腹圧性尿失禁の治療剤又は予防剤として有用な化合物を提供すること。【解決手段】本発明は、下記に代表されるインドール誘導体又はその薬学的に許容される酸付加塩を提供する。【選択図】なし