A compound of the formula (V): ##STR1## wherein Ar' is a halogenated phenyl group, R is a hydrocarbon residue having a functional group at the .alpha.-carbon, R.sup.3' is an optionally substituted aliphatic or aromatic hydrocarbon residue or an optionally substituted aromatic heterocyclic group, Y and Z are, the same or different, a nitrogen atom or a methine group optionally substituted with a lower alkyl group, and (R) and (S) represent configurations, which is an optically active intermediate for production of optically active triazole compounds (I): ##STR2## wherein the symbols have the same meanings as defined above, and methods of preparing the compounds (V) and (I).