The guanidinobenzoic acid derivatives of the general formula: ##STR1## wherein Z represents a carbon-carbon covalent bond, or a methylene, ethylene or vinylene group, R.sup.1 represents a hydrogen atom, or a straight- or branched-chain alkyl group containing from 1 to 4 carbon atoms, R.sup.2 represents a straight- or branched-chain alkyl group containing from 4 to 10 carbon atoms, or a cycloalkyl or cycloalkenyl or straight- or branched-chain alkenyl group containing from 3 to 8 carbon atoms, or a phenyl or benzyl group, or NR.sup.1 R.sup.2 represents a 4- to 8-membered heterocyclic ring, and acid addition salts thereof, have anti-plasmin and anti-trypsin activities.