PURPOSE: To increase the range of uses for waste edible oil by improvement of qualities of waste edible oil, by sufficiently removing impurities in the waste edible oil at a low cost.

CONSTITUTION: Waste edible oil is mixed with an aqueous solution of sodium hydroxide under stirring to afford an emulsion. saturated common salt water is added to the emulsion under stirring and the mixture is boiled. The mixture is divided into regenerated edible oil and an aqueous solution of impurities by allowing the mixture to allow to stand. The regenerated edible oil is mixed with an aqueous solution of sodium hydroxide and the mixture is heated. The resultant saponified product is dried.