A compound having HIV Integrase Inhibitory activity of the formula: (wherein: R1 is optionally substituted aralkyl; R2 and R3 are each independently hydrogen, optionally substituted alkyl, optionally substituted amino, optionally substituted alkenyl or optionally substituted alkoxy (provided that each substituent for “optionally substituted” is a noncyclic group); R4 is hydrogen, optionally substituted carboxy, optionally substituted formylamino, optionally substituted carbamoyl, optionally substituted amino (provided that a substituent on amino in “optionally substituted formylamino”, “optionally substituted carbamoyl” and “optionally substituted amino” may form an optionally-substituted N-atom containing heterocyclic ring together with an adjacent N atom), optionally substituted alkyl, optionally substituted alkenyl, optionally substituted aryl, or optionally substituted heteroaryl) or a salt thereof.