A method for producing optically active 2-substituted-1,2,3,4-tetrahydroquinolines, comprising reducing a quinoline compound represented by formula: (wherein R 1 represents an optionally substituted alkyl group, an optionally substituted aryl group, an optionally substituted aralkyl group, an optionally substituted cycloalkyl group or an optionally substituted heteroaryl group, R 2 represents a hydrogen atom, an optionally substituted alkyl group, an optionally substituted aryl group, an optionally substituted aralkyl group, an optionally substituted cycloalkyl group, an optionally substituted heteroaryl group, an optionally substituted hydroxyl group, an optionally substituted thiol group, an optionally substituted amino group, an optionally substituted carbamoyl group, an optionally substituted aryloxy group, an optionally substituted heteroaryloxy group, a carboxyl group, an esterified carboxyl group, a cyano group, a nitro group or a halogen atom, R 2 is bound to the quinoline ring at any one of positions 5 to 8, n is an integer of 1 to 4, and when n is not less than 2, R 2 groups adjacent to each other may join together to form a ring), in the presence of a hydrogen donor compound and an iridium complex having a chiral prolinamide compound as a ligand to give an optically active 2-substituted-1,2,3,4-tetrahydroquinoline represented by formula: (wherein R 1, R 2 and n are as defined in formula, and the symbol "*" indicates that the carbon atom is a chiral center), wherein the iridium complex having a chiral prolinamide compound as a ligand is represented by formula: Cp*Ir (L-H +) (wherein X represents Cl -, p-CH 3 C 6 H 4 SO 3 -, CH 3 SO 3 -, CF 3 SO 3 -, NO 3 -, BF 4 -, C10 4 -, PF 6 -, SbF 6 -, B[3,5-di(trifluoromethyl)phenyl] 4 - or B(4-fluorophenyl)4 -, L is a chiral prolinamide compound represented by formula: (wherein R 3 represents a hydrogen atom, an optionally substituted alkyl group, an optionally substituted aryl group, an optionally substituted aralkyl group, an optionally substituted cycloalkyl group or an optionally substituted heteroaryl group, and the symbol "*" indicates that the carbon atom is a chiral center), and Cp* represents (1,2,3,4,5-η)-pentamethyl-2,4-cyclopentadien-1-yl). (wherein R 1 represents an optionally substituted alkyl group, an optionally substituted aryl group, an optionally substituted aralkyl group, an optionally substituted cycloalkyl group or an optionally substituted heteroaryl group, R 2 represents a hydrogen atom, an optionally substituted alkyl group, an optionally substituted aryl group, an optionally substituted aralkyl group, an optionally substituted cycloalkyl group, an optionally substituted heteroaryl group, an optionally substituted hydroxyl group, an optionally substituted thiol group, an optionally substituted amino group, an optionally substituted carbamoyl group, an optionally substituted aryloxy group, an optionally substituted heteroaryloxy group, a carboxyl group, an esterified carboxyl group, a cyano group, a nitro group or a halogen atom, R 2 is bound to the quinoline ring at any one of positions 5 to 8, n is an integer of 1 to 4, and when n is not less than 2, R 2 groups adjacent to each other may join together to form a ring), in the presence of a hydrogen donor compound and an iridium complex having a chiral prolinamide compound as a ligand to give an optically active 2-substituted-1,2,3,4-tetrahydroquinoline represented by formula: (wherein R 1, R 2 and n are as defined in formula, and the symbol "*" indicates that the carbon atom is a chiral center), wherein the iridium complex having a chiral prolinamide compound as a ligand is represented by formula: Cp*Ir (L-H +) (wherein X represents Cl -, p-CH 3 C 6 H 4 SO 3 -, CH 3 SO 3 -, CF 3 SO 3 -, NO 3 -, BF 4 -, C10 4 -, PF 6 -, SbF 6 -, B[3,5-di(trifluoromethyl)phenyl] 4 - or B(4-fluorophenyl)4 -, L is a chiral prolinamide compound represented by formula: (wherein R 3 represents a hydrogen atom, an optionally substituted alkyl group, an optionally substituted aryl group, an optionally substituted aralkyl group, an optionally substituted cycloalkyl group or an optionally substituted heteroaryl group, and the symbol "*" indicates that the carbon atom is a chiral center), and Cp* represents (1,2,3,4,5-η)-pentamethyl-2,4-cyclopentadien-1-yl).