A compound represented by general formula (I) (wherein all symbols are as defined in the description) or a salt solvate N oxide form or prodrug thereof is a potent FXIa inhibitor has excellent oral absorption properties and kinetics in blood can exert a potent anti coagulation activity over a long period of time after being administered orally and has a discrepancy between the anti coagulation activity thereof and the CYP inhibiting activity thereof. Therefore the compound or the salt solvate N oxide form or prodrug thereof can be used as an efficient prophylactic and/or therapeutic agent for vascular occlusive diseases.
