A compound represented by the following general formula (1), or a salt thereof has serine protease inhibiting activity, and particularly excellent inhibiting activity against clotting factor VIIa. This compound or a salt thereof is useful as therapeutic and/or prophylactic agents for diseases associated with thrombus formation.
[wherein R
1
represents hydrogen, R
2
represents optionally substituted phenyl, etc., R
3
represents optionally substituted C6-10 aryl, etc.]