1(2H)-Isoquinolone compounds and acid addition salts thereof

1(2H)-Isoquinolone compounds represented by the formula (I) ##STR14## wherein Y represents hydrogen, chlorine or a methoxy group, Z represents a straight chain or branched chain divalent saturated aliphatic hydrocarbon group having 2 to 4 carbon atoms, R.sub.1 represents a cyano group, a lower alkoxycarbonyl group, a carbamoyl group, N-alkylcarbamoyl having 1 to 4 carbon atoms in the alkyl moiety, N,N-dialkylcarbamoyl having 1 to 4 carbon atoms in each alkyl moiety, 4-methylpiperazinocarbonyl or morpholinocarbonyl, a phenyl group or halophenyl or alkoxyphenyl having 1 to 4 carbon atoms in the alkoxy moiety, R.sub.2 represents hydrogen or a lower alkyl group, R.sub.3 represents a lower alkyl group, or R.sub.2 and R.sub.3 can form, when taken together with nitrogen atom to which they are attached, pyrrolidino, piperidino, 4-methylpiperazino, 4-hydroxyethylpiperazino or morpholino, and the pharmaceutically acceptable acid addition salts thereof.