It is an object of the present invention to provide an antitumor agent, which is further excellent as a treatment agent used in the prevention and/or therapy of tumor associated with a bromodomain, and also to provide a bromodomain inhibitor, which is useful as a treatment agent for diseases or states associated with a bromodomain.An antitumor agent and a bromodomain inhibitor, comprising a compound represented by the following formula, have an excellent bromodomain inhibitory activity and are useful as treatment agents in the prevention and/or therapy of tumor associated with a bromodomain, and the like:wherein R<；sup>；1<；/sup>；represents a C<；sub>；1-6<；/sub>；alkyl group, etc.； R<；sup>；2<；/sup>；represents a hydrogen atom, etc.； R<；sup>；3<；/sup>；represents a halogen atom, etc.； Z<；sup>；1<；/sup>；, Z<；sup>；2<；/sup>；and Z<；sup>；3<；/sup>；each represent CH, etc.； X<；sup>；1<；/sup>；represents CONH, etc.； Ring A represents a phenyl group, etc.； R<；sup>；4<；/sup>；represents a halogen atom, etc.； and m represents an integer from 0 to 5.
