PROBLEM TO BE SOLVED: To stably disperse an oil phase containing a solid oil component and a liquid oil component as fine particles in an aqueous solution without necessitating blending of a surfactant.SOLUTION: The oil phase containing the solid oil component and the liquid oil component is added to an aqueous phase containing a water-soluble thickener and kept at a temperature higher than the melting point of the solid oil component, at a temperature higher than the melting point of the solid oil component, and the mixture is sheared and mixed to a temperature below the melting point of the solid oil component.