To provide a purification method for obtaining a purified product of a phenylhydrazine-β-carboxylate compound (I) having little impurities by efficiently separating and removing impurities included in a crude product of the phenylhydrazine-β-carboxylate compound (I) while suppressing a loss of the phenylhydrazine-β-carboxylate compound (I).

A purification method of a phenylhydrazine-β-carboxylate compound (I) comprises: mixing a crude product of the phenylhydrazine-β-carboxylate compound (I) with water and an organic solvent that can be separated from water, in the presence of an acid; and then separating an oil layer containing the phenyl hydrazine-β-carboxylate compound (I) from a water layer.