The present invention relates to A nitrogen-containing heterocyclic compound represented by formula (I):wherein R1 represents lower alkyl which may be substituted with lower alkoxy, R2 represents formula (IV):wherein R7 represents lower alkanoyl, and R3 represents lower alkyl substituted with fluorine atom(s) or a pharmaceutically acceptable salt thereof. The said compounds can be useful in the prevention or treatment of a disease associated with the production of kynurenine.
