The present invention provides a nitrogen-containing aromatic heterocyclic derivative represented by formula (I): [wherein W represents CR3 (wherein R3 represents a hydrogen atom or the like) or the like, R4 represents a hydrogen atom or the like, R5 represents a hydrogen atom or the like, R9 represents substituted imidazolyl, R12 and R13 may be the same or different, each represent a hydrogen atom or the like, R22 and R23 may be the same or different, each represent a hydrogen atom or the like, R24 represents a hydrogen atom or the like, Y represents C—R25 (wherein R25 represents a hydrogen atom or the like) or the like] or a pharmaceutically acceptable salt thereof and a FGFR inhibitor comprising, as an active ingredient, the nitrogen-containing aromatic heterocyclic derivative or the pharmaceutically acceptable salt thereof, or the like.