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): (wherein R6 and R7 may be the same or different and each represent a hydrogen atom or the like, R8, R9, R10, 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, and R3 represents optionally substituted aryl or an optionally substituted heterocyclic group).