The present invention provides a production method of a fine O/W emulsion external preparation having the emulsion particle size of 50 to 500 nm comprising the steps of: mixing with stirring, at 70 to 80 °C, (A) a hydrophilic nonionic surfactant, (B) a linear higher alcohol having 16 or more carbon atoms, (C) an oil component, (D) an aqueous solvent which can be soluble in water, wherein the critical micelle concentration (c.m.c.) of the hydrophilic nonionic surfactant in the aqueous solvent is higher than that in water, and (E) water in the amount of 5 to 25 mass % of the total amount of (A) to (E), to prepare a W/O emulsion and adding, while mixing with stirring, (F) water or an aqueous formulation at 10 to 35 °C into the W/O emulsion to invert the W/O emulsion to a fine O/W emulsion. The production method needs not to use any cooling apparatus, has excellent economical efficiency, can easily produce a fine O/W emulsion external preparation excellent in safety and stability.
