A drug is provided that is useful as a preventive or therapeutic for cancer as a result of having superior PI3K inhibitory effects as well as superior stability in the body and water-solubility. A compound, or pharmaceutically acceptable salt thereof, represented by formula (I): [wherein, X represents a single bond, etc.； Y represents a single bond, etc. (provided that X and Y are not simultaneously single bonds)； Z represents a hydrogen atom, etc.； m represents an integer of 1 or 2； and R 1 represents a cyclic substituent].
