TECHNOLOGY FOCUS - POLYMERS - Preferred Components: The PVDF resin has weight average molecular weight (Mw) of 50000-500000. The PVDF resin is copolymerization polymer that contains greater than or equal to 30 mol.% of vinylidene fluoride homopolymer or vinylidene fluoride. Preferred Membrane: The hollow fiber has internal diameter of 0.1-5 mm and external diameter of 0.15-6 mm. The hollow fiber has contact angle of 15-44 degrees and pure water permeability of 800-1200 (l/m2 hour). Piles of irregular aggregate forms are connected with each other inside the separation membrane, gaps split between piles having average length of 1-100 mu m, support layer having amorphous structure, which has macropores having average width of 0.1-10 mu m, is formed and branch-type structure layer and separation active layer are sequentially formed on the support layer. The support layer is composed of the form of aggregates that are formed by thermally-induced phase separation method or modified thermally-induced phase separation method. The branch-type structural layer is composed of pores having size of 5-100 mu m. The separation active layer is composed of pores having size of 0.001-0.1 mu m and thickness of 0.1-5 mu m. Preferred Method: The temperature is maintained at 80-200 degrees C while preparing the spinning solution. The coagulant used in the coagulation process is water or mixed solution between water and at least one organic solvent selected from dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide and dimethyl acetamide; and maintained at 20-50 degrees C. The method additionally involves after preparing the spinning solution; discharging internal coagulant in it from triple nozzle; discharging a good solvent at less than or equal to 50 degrees C externally; discharging thermosetting resin solution from nozzle between inside and outside; or after preparing the spinning solution, discharging internal coagulant in it from dual nozzle, discharging the thermosetting resin solution externally to be coagulated, continuously allowing the thermosetting resin solution to pass through a good solvent and then allowing the thermosetting resin solution to pass through non-solvent. The spinning solution is composed of 20-60 wt.% thermosetting resin, 30-50 wt.% poor solvent, 0.1-20 wt.% at least one of organic additive and inorganic additive, 0.1-5 wt.% non-solvent and 0.01-1 wt.% of surfactant. EXAMPLE - No suitable example given.