A heterocyclic compound or one of its salts represented by the formula (1): wherein R2 represents a hydrogen atom or a C1-C6 alkyl group； A represents a C1-C6 alkylene group or a C2-C6 alkenylene group； and R1 represents a heterocyclic group selected from a saturated or unsaturated heteromonocyclic group having 1 to 4 heteroatoms selected from the group consisting of a nitrogen atom, an oxygen atom and a sulfur atom； where at least one group selected from the group consisting of groups (1) to (66) below may be present as a substituent in the aromatic group represented by R1: (1) a C1-C6 alkyl group, (2) a C2-C6 alkenyl group, (3) a halogen substituted C1-C6 alkyl group, (4) a C1-C6 alkoxy group, (5) an aryloxy group, (6) a thio (C1-C6) alkyl group, ( 7) a halogen-substituted C1-C6 alkoxy group, (8) a hydroxy group, (9) a protected hydroxy group, (10) a C1-C6 hydroxyalkyl group, (11) a protected C1-C6 hydroxyalkyl group, (12 ) a halogen atom, (13) a cyano group, (14) an aryl group, (15) a nitro group, (16) an amino group, (17) an amino group that has one or more groups selected from the group that it consists of a C1-C6 alkyl group, a C1-C6 alkanoyl group, a (C1-C6) alkoxy group, a (C1-C6) alkyl sulfonyl group, a carbamoyl group, a (C1-C6) carbamoyl alkyl group, a C1-C6 aminoalkanoyl group, a (C1C6) alkanoyl group at C1-C6 minoalkanoyl and a C1-C6 alkoxycarboxylaminoalkanoyl group as substituents, (18) a C1-C6 alkanoyl group, (19) an arylsulfonyl group which may have one or more C1-C6 alkyl groups in the group aryl, (20) a carboxy group, (21) a C1-C6 alkoxycarbonyl group, (22) a C1-C6 carboxyalkyl group, (23) a C1-C6 alkoxy (C1-C6) alkylaryl group, (24 ) a C1-C6 alkanoyl (C1-C6) aminoalkanoyl group, (25) a C2-C6 carboxyalkenyl group, (26) a C2-C6 alkoxy (C1-C6) alkoxy group, (27) a C2-C6 carbamoylalkenyl group which it may have one or more groups selected from the group consisting of a C1-C6 alkyl group and a halogen substituted C1-C6 alkyl group, (28) a carbamoyl gr
