PROBLEM TO BE SOLVED: To develop a surface treating agent that achieves both of dispersibility in various kinds of oil agents and adhesion property to skin, and to use the agent as a surface treating agent for cosmetic powder.SOLUTION: A resin composition is obtained from carnauba wax by fractionation and has a resin concentration of 15 to 40 mass%, a softening point of 57 to 80°C and an iodine number of 25 to 50. By using the resin composition as a surface treating agent for powder, the powder develops water repellency and dispersibility in an oil agent even with a small amount of the agent and shows excellent adhesiveness to skin. In particular, the composition is suitable for the surface coating treatment of metal oxide such as titanium oxide and iron oxide.
