PURPOSE: To obtain an oiling agent, consisting of an aqueous emulsion containing a specific silicon oil, aliphatic monocarboxylic acid salt and polyoxyethylene alkyl phenyl ether as an emulsifying agent and capable of imparting wetting characteristics and melt sticking resistance to carbon fibers by application thereto.

CONSTITUTION: An aqueous emulsion rich in long-period stability is prepared by using (A) a silicone oil (preferred example; dimethyl silicone) which is a simple substance or mixture having ≤100cst viscosity at 25°C as a principal component with (B) an essential emulsifying agent consisting of an 8W18C aliphatic monocarboxylic acid amine salt and a polyoxyethylene alkyl phenyl ether at 95W75/5W25 ratio of the components (A)/(B). This emulsion is then applied to carbon fibers during steps ranging from spinning to infusibilizing thereof to exhibit wetting characteristics, improved process passableness and impart excellent melt sticking resistance especially to the above-mentioned fibers.