The present invention provides a novel bicyclic or tricyclic heterocyclic compound represented by the formula (I) wherein ring A is an optionally substituted aromatic group, one of X 1 and X 2 is a carbon atom, and the other is a nitrogen atom, X 3 is a nitrogen atom, or CR 2 , X 4 is a nitrogen atom, or CR 3 , X 5 is a sulfur atom, or -CH=CH-, Z 1 is an oxygen atom, -C(R 6 )(R 7 )-, -NH-, -C(R 6 )(R 7 )-NH-,-NH-C(R 6 )(R 7 )-, -C(R 6 )(R 7 )-O-, -O-C(R 6 )(R 7 )-, or a single bond, one of Z 2 and Z 3 is CH and the other is a nitrogen atom, or both are nitrogen atoms, and other symbols are as defined in the DESCRIPTION, or a pharmacologically acceptable salt thereof.