The present invention provides an integrase inhibitor. The inventors have have found the following compound of formula (I) possessing an integrase inhibitory activity. <；CHEM>； (wherein, R <；C>； and R <；D>； taken together with the neighboring carbon atoms form a ring which may be a condensed ring, Y is hydroxy, mercapto or amino； Z is O, S or NH ； R <；A>； is a group shown by <；CHEM>； (wherein, C ring is N-containing aromatic heterocycle) or the like)
