POROUS HOLLOW FIBER MEMBRANE

A porous hollow fiber membrane is provided for the treatment of a protein-containing liquid, which can effectively separate and remove a substance such as a small diameter virus, and which can allow effective permeation of a useful substance to be recovered such as protein in high concentration. The porous hollow fiber membrane has an asymmetric structure having a dense layer in an outer layer only and contains a hydrophobic polymer and a first hydrophilic polymer, the surface and the porous part of the hollow fiber membrane are coated with a second hydrophilic polymer, the hydrophobic polymer is a polysulfone-type polymer, the first hydrophilic polymer is a copolymer of vinylpyrrolidone with vinyl acetate, and the second hydrophilic polymer is a polysaccharide or a polysaccharide derivative. The porous hollow fiber membrane is obtained by co-dissolving the hydrophobic polymer and the first hydrophilic polymer and then the second hydrophilic polymer is coated.