A process for producing optically active pyridineethanol derivatives at a high yield which comprises stereoselectively reducing acetylpyridine derivatives by treating with an enzyme or an enzyme source having an asymmetric reduction activity; the enzyme having the asymmetric reduction activity; a DNA encoding the enzyme; a recombinant vector containing the DNA; a transformant containing the recombinant vector; and a process for producing optically active pyridineethanol derivatives from optically inactive pyridineethanol derivatives with the use of the above-described enzyme or transformant.