A condensed heterocyclic compound having poly(adenosine 5'-diphospho-ribose)polymerase (PARP) inhibitory activity represented by the formula (I): wherein R1 is hydrogen, halogen, lower alkyl or lower alkoxy, A and two adjacent carbon atoms of the six membered ring to be bonded with A form benzene ring, pyridine ring, etc, -Y1=Y2- is formula (II) wherein L11, L12, L13 and L14 is (1) lower alkylene, (2) lower alkenylene, etc, and R21, R22 , R23 and R24 is (1) cyclic amino group, which is substituted with phenyl optionally substituted with one or more suitable substituent(s), etc. provided that when A and two adjacent carbon atoms of the six membered ring to be bonded with A form benzene ring, then -Y1=Y2- is formula (III) or its prodrug, or their salts.