Disclosed is a low-molecular-weight compound having an EPO production-promoting activity and/or a hemoglobin expression-enhancing activity. Specifically disclosed is an EPO production promoter and/or a hemoglobin expression enhancer comprising a 1-acyl-4-(phenoxy, benzyloxy or phenylamino)-1,2,3,4-tetrahydroquinoline derivative, more specifically a tetrahydroquinoline compound represented by the general formula (1); [wherein R1, R2, R2′, R3 and R3′ independently represent a hydrogen atom, a C1-6 alkyl group, or the like; R4, R5, R6, R7, R8, R9 and R10 independently represent a hydrogen atom, a halogen atom, a C1-6 alkyl group, or the like; A represents N—R11 or an oxygen atom; R11 represents a hydrogen atom, a C1-6 alkyl group, or the like; and n represents an integer of 0 or 1], a salt of the tetrahydroquinoline compound, or a solvate of the tetrahydroquinoline compound or the salt.