A condensed
purine derivative represented by Formula (I): wherein X—Y-Z represents R1N—C═O or N═C—W, R2 represents a
hydrogen atom, a substituted or unsubstituted lower
alkyl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted
aryl group, a substituted or unsubstituted aromatic heterocyclic group, a substituted or unsubstituted alicyclic heterocyclic group or the like, n represents an integer of from 0 to 3, V1 represents a
hydrogen atom, a substituted or unsubstituted lower
alkyl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted
aryl group, or a substituted or unsubstituted aromatic heterocyclic group, V2 represents a substituted lower
alkyl group or a substituted or unsubstituted aromatic heterocyclic group, and when V1 represents a
hydrogen atom, a lower alkyl group, a substituted or unsubstituted aralkyl group, or a substituted or unsubstituted
aryl group, and for example, X—Y-Z represents R1aN—C═O and R2 represents a substituted lower alkyl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted alicyclic heterocyclic group, a
halogen atom, a lower alkylthio group, —NR7R8, —CO2H, a lower alkoxycarbonyl group, —COHal, —CONR9R10 or —CHO, V2 may represent a lower alkyl group, a substituted or unsubstituted aralkyl group, or a substituted or unsubstituted aryl group; or a pharmacologically acceptable salt thereof.