Abstract: A compound of the general formula (I): [wherein, R1 represents a halogen atom, or the like, R2 represents a hydrogen atom, or the like, R3 and R4, each independently, represent a hydrogen atom, a C1-4 alkyl group, or the like, R5 represents a hydrogen atom, a halogen atom, or the like, R6 represents a hydrogen atom, a halogen atom, or the like, R7 and R8, each independently, represent a hydrogen atom, a halogen atom, or the like, R9 and R10, each independently, represent a hydrogen atom, a C1-4 alkyl group, R11 and R12, each independently, represent a hydrogen atom, a C1-4 alkyl group, or the like, X represents an oxygen atom, a group —CH2—, or the like, Y represents a nitrogen atom, a group ?CH—, or the like, and Z represents a nitrogen atom, or the like] or a pharmacologically acceptable salt thereof, which has an excellent suppressive action on platelet aggregation, and is useful for prevention and/or treatment of thromboembolism.