A nitrogen-containing heterocyclic compound represented by the formula (I): {wherein R50 and R51 may be the same or different and each represents a hydrogen atom, optionally substituted C1-10 alkoxy or halogen, or R50 and R51 are combined together with the two respective adjacent carbon atoms to form ring A selected from a benzene ring, a naphthalene ring and a pyridine ring (wherein ring A can have a substituent or substituents, the number of which is 1 to the substitutable number, and the substituent (s) may be the same or different and each is halogen, optionally substituted C1-10 alkyl or optionally substituted C1-10 alkoxy), G1 and G2 may be the same or different and each represents an atom of nitrogen or CH, with the proviso that G1 and G2 do not represent CH at the same time, X represents formula (III): where m1 and m2 can be the same or different and each represents an integer 0 or 1, Y represents an oxygen atom, -S (O) m3- (where m3 represents an integer from 0 to 2) or -NR8- (where R8 represents an optionally substituted hydrogen or C1-10 alkyl atom ), and R6 and R7 may be the same or different and each represents a hydrogen atom, halogen, cyano, carboxy, optionally substituted C1-10 alkyl, optionally substituted cycloalkyl, optionally substituted aryl, an optionally substituted heterocyclic group, C1- alkanoyl 8 optionally substituted, optionally substituted (C1-10) alkoxycarbonyl or -CONR12R13 (wherein R12 and R13 may be the same or different and each represents an optionally substituted hydrogen or C1-10 alkyl atom, or R12 and R13 are combined together with the adjacent nitrogen atom to form an optionally substituted nitrogen-containing heterocyclic group), R1 represents optionally substituted C1-10 alkyl, optionally substituted C2-10 alkenyl, optional C2-10 alkynyl optionally substituted, optionally substituted cycloalkyl, optionally substituted aryl, an optionally substituted heterocyclic group or -NR24R25 (wherein R24 and R25 may be the same or diffe
