methallylsulfonic acid styrenesulfonic acid or a metallic salt of one of the last three vinyl compounds a process for producing acrylic fiber comprises the steps of spinning a spinning solution of an an polymer as mentioned above in a solvent therefor according to the known wet dry or dry jet wet process and subjecting the resulting coagulated filaments to the steps including drawing water washing and drying to form a fiber in this process low velocity spinning multistep drawing etc are favorably adopted for the purpose of obtaining a denser fiber in this process for producing acrylic fiber the above mentioned oiling agent may be used as a processing oil in the steps succeeding water washing and drawing or as a finishing oil after drying it may also be used after forming fiber when it is used as the processing oil it is desired to comprise a combined oil component selected from among those having antistatic properties such as nonylphenol cationic oil and fatty acid esters and those capable of providing smoothness such as wax and adducts of a higher alcohol with ethylene oxide when it is used as the finishing oil it is desired to comprise a mineral oil an adduct of an higher alcohol with ethylene oxide or a neutral oil for providing a uniform applicability in addition to one having antistatic properties and one capable of providing smoothness the neopentyl alcohol derivative as the indispensable component of the oiling agent to be used in the process of the present invention has an excellent performance in respect of thermal resistance amount of heating residue amount of heat generation and degree of densification of the resulting fiber etc therefore it exhibits very excellent effects of preventing acrylic fiber precursor for production of a carbon.