An optically active propargyl alcohol derivative of the formula (I) ##STR1## wherein X=phenyl or thienyl and R=lower alkyl, halogenated methyl, phenyl or substituted phenyl having at least one lower alkyl radical and or halogen atom, is prepared by contacting a racemic modification of l- and d-isomers of the formula (I) with l-brucine in an organic solvent, by separating the resultant deposited diastereomer from a solution containing the resultant other diastereomer in the organic solvent, by decomposing each diastereomer with an aqueous mineral acid solution in the presence of an organic solvent capable of dissolving the corresponding optically active isomer dissociated from the diastereomer and incompatible with water so as to allow the optically active isomer to be dissolved in the water-incompatible organic solvent, and by recovering the optically active isomer from the solution thereof.