Provided is a kynurenine production inhibitor comprising a nitrogen-containing heterocyclic compound represented by formula (I):
(wherein R
50
and R
51
may be the same or different and each represent a hydrogen atom or the like, G
1
and G
2
may be the same or different and each represent a nitrogen atom or the like, X represents formula (III):
(wherein m
1
and m
2
may be the same or different and each represent an integer of 0 or 1, Y represents an oxygen atom or the like, and R
6
and R
7
may be the same or different and each represent a hydrogen atom or the like),
R
1
represents optionally substituted lower alkyl or the like, R
2
represents a hydrogen atom or the like, and R
3
represents optionally substituted lower alkyl or the like), and the like.