<；P>；PROBLEM TO BE SOLVED: To provide a W/O type micro-emulsion containing water finely and stably dispersed in various kinds of oils with no need of application of strong mechanical outside force or no need of using a plurality of surfactants or co-surfactants. <；P>；SOLUTION: The W/O type micro-emulsion is a W/O type micro-emulsion containing a bio-surfactant. The W/O type micro-emulsion is a micro-emulsion containing a bio-surfactant produced in a large quantity from reproducible resource by microorganism, has a large particle diameter of water droplets dispersed in an oil, and is thermodynamically stable. The W/O type micro-emulsion can be obtained efficiently at a low cost with no need of adding a plurality of surfactants and co-surfactants in large quantities or no need of loading intense mechanical energy. Further, the W/O type micro-emulsion can be used in a wide range of spheres for emulsion fuels, cosmetics such as cleansing oil, medical products and food. <；P>；COPYRIGHT: (C)2008,JPO&INPIT
