The present invention relates to a compound represented by Formula [I]: wherein X is O, S, NH or CH2; Y1, Y2, Y3, Y4 and Y5, which may be identical or different, are each CH or N; however, at least one of Y1, Y2, Y3, Y4 and Y5 is N; Z1 and Z2, which may be identical or different, are each CH or N; n is an integer from 1 to 3; R1 is a C3-C8 cycloalkyl group, a C6-C10 aryl group, an aliphatic heterocyclic ring or an aromatic heterocyclic ring, or a bicyclic aliphatic saturated hydrocarbon group; R2 and R3, which may be identical or different, are each a hydrogen atom, a lower alkyl group, a lower alkenyl group, a C3-C8 cycloalkyl group, a C6-C10 aryl group, an aromatic heterocyclic ring, or the like; and R4 is a hydrogen atom, a lower alkyl group, a C3-C6 cycloalkyl group or the like, or a pharmaceutically acceptable salt or ester thereof, and a selective inhibitor against Cdk4 and/or Cdk6 or an anticancer agent containing the compound or a pharmaceutically acceptable salt or ester thereof.