To provide a compound which has a potent agonistic activity on GHS-R and which is useful as a therapeutic agent for systemic wasting diseases such as cachexia. A 3,8-diaminotetrahydroquinoline derivative represented by formula (la) (wherein X represents CH 2 , C=O, CH-OR, CH-SR, or CH-NRR'； m is a number of 1 or 2； Ar represents a phenyl group, a naphthyl group, a 5-membered or 6-membered aromatic heterocyclic group having one or two elements selected from S, N, and O, or a similar group； R 1 and R 2 , which may be identical to or different from each other, each represent a hydrogen atom or a methyl group； R 3 represents a C1 to C6 alkyl group or a similar group； n is a number of 0 or 1； R 4 and R 5 , which may be identical to or different from each other, each represent a hydrogen atom, or a C1 to C6 alkyl group, etc.； and R 6 , R 7 , R, and R', which may be identical to or different from one another, each represent a hydrogen atom or a C1 to C6 alkyl group), or a salt thereof.本發明提供一種具有強力的GHS-R促效劑作用、且可用作惡病質等全身性消耗性疾病治療藥之化合物。本發明係關於一種以通式(1a)所表示之3,8-二胺基四氫喹啉衍生物或其鹽：(式中，X表示CH2、C=O、CH-OR、CH-SR或CH-NRR'；m表示1或2之數；Ar表示苯基，萘基，含有選自S、N及O中的1個或2個之5員環或6員環之芳香族雜環基等；R1與R2相同或不同，表示氫原子或甲基；R3表示碳數1~6之烷基等；n表示0或1之數；R4與R5相同或不同，表示氫原子、碳數1~6之烷基等；R6、R7、R及R'相同或不同，表示氫原子、碳數1~6之烷基)。
