<p>Particularly in the recovery and reuse of unreacted serine after the synthesis of phosphatidylserine by the transfer reaction of a phosphatidyl group with phospholipase D, a simple process for recovering serine in which a material inhibitory to the synthesis of phosphatidylserine can be efficiently removed is provided. The present invention provides the following processes for recovering serine polar organic solvent or a mixture of a polar organic solvent and water is added to the unreacted serine containing water-soluble fraction in which the phosphatidylserine has been removed from a reaction mixture in the reaction system and the fraction with the added solvent or the mixture of the solvent and water is washed to obtain the serine.</p>
