A 3,8-diaminotetrahydroquinoline derivative represented by formula (1 a): ** Formula ** (where X represents CH2, C>； = O, CH-OR, CH-SR, or CH-NRR '； m is a 1 or 2 number； 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 condensed aromatic heterocyclic group formed between a ring of benzene and a 5-membered or 6-membered heterocyclic ring having one or two elements selected from S, N and O (where the phenyl, naphthyl or aromatic heterocyclic groups may be substituted with 1 to 3 halogen atoms, a C1 alkyl group to C6, or a C1 to C6 alkoxy group)； R1 and R2, which may be identical or different from each other, each represent a hydrogen atom or a methyl group； R3 represents a C1 to C6 alkyl group (the alkyl group being optionally substituted with a methylthio or benzyloxy group), a phenyl group, a phenyl-a group C1-4 alkyl or an indolyl-C1-4 alkyl group (the phenyl group or the indolyl group being optionally substituted with a C1 to C6 alkyl group, a halogen atom or a C1 to C6 alkoxy group)； n is a number of 0 or 1； R4 and R5, which may be identical or different from each other, each represent a hydrogen atom, or a linear, branched or cyclic C1 to C6 alkyl group (the alkyl group being optionally substituted with a halogen atom, a hydroxyl group, a C1 to C6 alkoxy group, a phenyl group, a benzyloxy group or a hydroxyphenyl group), or R4 or R5, and R6 or R7 can be attached to the adjacent nitrogen atom to form a pyrrolidine ring or a piperidine ring (where the pyrrolidine ring or the piperidine ring optionally substituted with a hydroxyl group)； R6 and R7, which may be identical or different from each other, each represent a hydrogen atom or a C1 to C6 alkyl group； and R and R ', which may be identical or different from each other, each represent a hydrogen atom or a linear, branched or cyclic C1 to C6 alkyl group) or a salt thereof.Un derivado de 3,8-diaminot
