PURPOSE: To obtain the subject fiber excellent in operating efficiency and adhesion to matrix resins by coating the surface of wholly aromatic fiber in which a solid cation exchangeable inorganic compound is adhered to the surface thereof with a specific Pluronics(R) mixture having a specified composition.

CONSTITUTION: The objective fiber obtained by coating the surface of wholly aromatic polyamide fiber (e.g. copoly p-phenylene.3,4'- oxydiphenylene.terephthalamide fiber) in which a solid cation exchangeable inorganic compound (e.g. silica-alumina) is adhered to the surface thereof with Pluronics(R) consisting of 70-95wt.% Pluronics A(R) of propylene oxide(PO) and ethylene oxide(EO) at (70/30)-(0-100) copolymerization molar ratio having 400-800 average molecular weight and 30-5wt.% Pluronics B(R) having 8000-30000 average molecular weight. Furthermore, the copolymerization molar ratio of the PO to the EO in the Pluronics B(R) is preferably (70-30)-(10-90).