An antitumor agent for combined use of a compound or pharmaceutically acceptable salt thereof represented by Formula (I) and a compound or pharmaceutically acceptable salt thereof represented by Formula (II) exhibits an excellent antitumor effect compared to cases where these are individually used, and exhibits antitumor effects against various cancer types:wherein R1 is azetidinyl and the like, R2 to R5 is a hydrogen atom or a halogen atom, R6 is C3-8 cycloalkyl and the like, R7 is a hydrogen atom and the like, and R8 is a halogen atom and the like.
