PURPOSE: To suppress the production of by-product, to facilitate the stirring in a slurrying reaction and to obtain an optically active 2-(4-hydroxyphenoxy) propionic acid useful as an intermediate for herbicide in high optical purity and yield.

CONSTITUTION: Hydroquinone(HQ) is added with 1.5-2 times mol of NaOH and then with 0.2-0.5 times mol each of Na salt of optically active 2- chloropropionic acid(CPA) or an optically active CPA and NaOH to perform the 1st stage reaction. The reaction mixture is added with 0.5-1.0 times mol (based on the charged HQ) of NaOH or 0.1-1 pt.wt. of NaCl and/or LiCl to effect the salting-out of the produced Na salt of optically active 2-(4- hydroxyphenoxy)propionic acid(HPPA) and the precipitated salt is added with 0.5-0.8 times mol each of Na salt of optically active CPA or optically active CPA and NaOH to perform the 2nd stage reaction. The objective optically active HPPA can be produced at a low cost while preventing the salting-out and precipitation of Na salt of HQ as hard crystal by this process.