A process for producing optically active quinuclidinol derivatives characterized by treating racemic 3-quinuclidinol esters represented by general formula (I) (wherein R represents linear or branched alkyl; and (H ) means an optional formation of a salt with a mineral or organic acid) with cells of microorganisms belonging to the genus Aspergillus, Rhizopus, Candida or Pseudomonas and capable of asymmetrically hydrolyzing the ester bond, liquid cultures of the microbial cells, treated microbial cells, enzymes produced by these microorganisms, or enzymes of swine or bovine origin. This process makes it possible to easily produce optically active 3-quinuclidinol derivatives which are valuable intermediates in synthesizing drugs, etc.