The present invention provides a nitrogen-containing heterocyclic compound or a pharmaceutically acceptable salt thereof having an inhibitory effect on the production of kynurenine, represented by formula (I):(whereinR6 and R7 may be the same or different and each represent a hydrogen atom or the like,R8, R9, R19, and R11 may be the same or different and each represent a hydrogen atom or the like,R1 represents lower alkyl which may be substituted with cycloalkyl, or the like, andR3 represents optionally substituted aryl or an optionally substituted heterocyclic group).
