Provided is a compound represented by general formula (I), or a pharmaceutically acceptable salt thereof, having superior monoacylglycerol acyltransferase-2 inhibitory activity. In formula (I), ring (A) represents a partially saturated heteroaryl group, an aryl group, or a heteroaryl group； RB represents a C4-18 alkyl group, a C3-8 cycloalkyl group, a partially saturated aryl group, an aryl group, or formula (II) (in formula (II), V represents the formula -CR11R12-, the formula -CO-, the formula -CO-O-, or the formula -CO-NH-； W represents a single bond or a C1-3 alkylene group； and the ring (B) represents a C3-8 cycloalkyl group, a C3-8 cycloalkenyl group, a partially saturated heteroaryl group, a saturated heterocyclyl group, an aryl group, or a heteroaryl group)； Y represents a nitrogen atom or formula N+(RF)； RF represents a C1-4 alkyl group； and m and n may be the same or different and each independently represent an integer 0 or 1.本發明提供一種化合物或其製藥學上容許之鹽，其具有優良之單醯基甘油醯基轉移酶2抑制作用，且係以下述一般式(I)表示。[式中，環A表示部分飽和之雜芳基、芳基或雜芳基；RB表示C4-18烷基、C3-8環烷基、部分飽和之芳基、芳基或下述式(II)；(式中，V表示式-CR11R12-、式-CO-、式-CO-O-或式-CO-NH-；W表示單鍵或C1-3伸烷基；環B表示C3-8環烷基、C3-8環烯基、部分飽和之雜芳基、飽和之雜環基、芳基或雜芳基)；Y表示氮原子或式N+(RF)；RF表示C1-4烷基；m及n係相同或相異地表示0~1之整數]。
