The present invention provides an integrase inhibitor. The inventors have have found the following compound of formula (I) possessing an integrase inhibitory activity.
1
(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
2
(wherein, C ring is N-containing aromatic heterocycle) or the like)