The present invention relates to a method for preparing an optically active 4-hydroxy-1,2,3,4-tetrahydroquinoline compound [I], which comprises the steps of:treating a racemic 4-hydroxy-1,2,3,4-tetrahydroquinoline compound represented by general formula [I]:[wherein R1 represents a hydrogen atom or a protecting group for amino group.]with an enzyme having an ability of selectively or preferentially acylating one enantiomer of the racemiccompound [I] in the presence of an acyl donor andif necessary, subjecting the reaction product to solvolysis.
