PROBLEM TO BE SOLVED: To provide a 3-substituted proline derivative having excellent FXIa inhibitory activity and useful as a therapeutic agent for thrombosis or the like, and its pharmaceutically acceptable salt.SOLUTION: This invention relates to a compound represented by formula (1) or its pharmaceutically acceptable salt, where a ring Q represents a group represented by the formula (2a) or the like.COPYRIGHT: (C)2015,JPO&INPIT【課題】優れたFXIa阻害活性を有し、血栓症等の治療薬として有用な3位置換プロリン誘導体及びその薬学上許容される塩の提供。【解決手段】式(1)で表される化合物またはその薬学上許容される塩。[式中、環Qは下記式(2а‘)で表される基等を表す。]【選択図】なし