A method wherein the separability between a polyether phase and a water phase is improved when a water-soluble compound is extracted and removed from a polyether containing the water-soluble compound with water is provided. The method comprises producing a polyether including a step of extracting and removing a water-soluble compound from a polyether containing the water-soluble compound with water, wherein the step includes at least an operation of separating a water phase from a polyether phase at a temperature of 50° C.