The present invention relates to a dibenzodiazepine derivative of formula (1) wherein ring Q1and ring Q2are independently selected from optionally-substituted benzene ring and optionally-substituted pyridine ring Rais hydrogen atom, or C1-6alkyl which may be optionally substituted with the same or different 1 to 3 halogen atoms n is 0,1, or 2 m is 1, 2, 3, or 4 and Rbis, independently when it exists plurally, hydrogen atom, C1-6alkyl which may be optionally substituted with the same or different 1 to 3 halogen atoms, or a pharmaceutically acceptable salt thereof, which is useful as a medicament for treating and/or preventing a central nervous system disease.本發明係關於一種可用作中樞神經系統疾病之治療劑及/或預防劑的式(1)所表示之二苯并二氮呯衍生物及其製藥學上所容許之鹽。 [式中,環Q1及環Q2分別獨立地表示可經取代之苯環、或可經取代之吡啶環;Ra表示氫原子、或者可經同種或異種之1~3個鹵素原子取代之C1-6烷基;n表示0、1或2;m表示1、2、3或4;Rb於存在複數個之情形時,分別獨立地表示氫原子、鹵素原子、或者可經同種或異種之1~3個鹵素原子取代之C1-6烷基]無
