An epoxy compound of the formula (1): ##STR00001## wherein, R represents a hydrogen atom or an alkyl group having 1 to 12 carbon atoms, and Ar represents an optionally substituted aromatic group, can be purified by dissolving a crude product containing the epoxy compound (1), an aprotic polar solvent and an alkali metal salt in a two-phase solvent composed of water and an organic solvent, which is capable of phase-separating from water, obtaining the organic layer by phase separation, washing with water and then subjecting to isolation of the epoxy compound (1) without decomposition.