The present invention relates to an oil-in-water (O/W) type nano-emulsion composition comprising an oil component containing oil and a polyethylene glycol ester-based emulsifier; and a water component containing a polyol or a polyol derivative. The present invention also relates to a cosmetic composition comprising the oil-in-water type nano-emulsion composition, and to a method for preparing the oil-in-water type nano-emulsion composition. According to the present invention, a nano-sized low-viscosity emulsion having a high inner phase can be obtained through the method that is different from the conventional methods of phase inversion temperature emulsification or high pressure emulsification, thereby significantly improving the stability of the emulsion. In addition, the nano-emulsion composition of the present invention can be added to a variety of cosmetic compositions having a variety of methods of use and can thus deliver active ingredients to the skin effectively since it has small-sized particles.