Abstract: A method of manufacturing a microporous hollow fiber having a high permeability to water characterized in that a spinning solution of (A) polyacrylonitrile, (B) an acrylonitrile copolymer, or (C) an admixture of (A) and (B) in an organic solvent is extruded from an annular slit, while simultaneously extruding an organic core liquid which is a solvent for (A), (B) and (C) or a swelling agent capable of swelling them from an orifice encircled by the annular slit and introducing the extruded spinning solution with the core liquid into an aqueous coagulating bath to coagulate the spinning solution to form the hollow fiber.

Abstract: A method of manufacturing a hollow fiber includes the steps of:extruding a spinning solution of high molecular weight compound dissolved into a solvent, from an annular slit; and simultaneously extruding a liquid consisting of at least one of the solvent and swelling liquid capable of swelling the high molecular weight compound from an orifice encircled by the annular slit.