A novel glycerol derivative, a process for preparing the same, and a process for preparing a triazole derivative. An optically active 2-arylglycerol derivative which is novel and useful as a synthetic intermediate of medicament is provided, and furthermore, (R)-2-(2,4-difluorophenyl)-3-(1H-1,2,4-triazole-1-yl)-propane-1,2-diol, which is useful as an antifungal agent, is prepared.