A compound of a formula (1) and pharmacologically acceptable salts thereof: ##STR1##

wherein R¹ represents hydrogen, halogen, alkyl or hydroxyl; R² represents hydrogen or halogen; R³ represents hydrogen, alkyl, hydroxyl, carboxyalkyl, alkoxycarbonylalkyl, alkylsulfonyl, alkoxycarbonylalkylsulfonyl, craboxyalkylsulfonyl or carboxyalkylcarbonyl; each of R⁴ and R⁵ represents hydrogen, halogen, alkyl, carbamoyl, alkoxy, carboxyl, alkoxycarbonyl, monoalkylcarbamoyl or dialkylcarbamoyl; R⁶ represents a heterocycle, hydrogen, alkyl, cycloalkyl, aralkyl, carboxyalkyl, alkoxycarbonyalkyl, aliphatic or aromatic acyl, carbamoyl, alkylsulfonyl, aryl, formimidoyl, 1-iminoalkyl, N-alkylforminidoyl or iminoarylmethyl; each of R⁷ and R⁸ represents hydrogen or alkyl; n represents 0, 1 or 2. The compound exhibits excellent activated blood coagulation factor X inhibitory activity and prevents or treats blood coagulation-related diseases.