Microfiltration membranes are used in sterilization and pretreatment processes in the bio industry, and demand is
increasing as the industrial scale is rapidly growing. The microfiltration membrane with high water permeability with an optimized pore size is used to improve the productivity of the process. Poly(ethersulfone) is suitable as a membrane material because of its excellent mechanical properties and thermal properties, but due to its weak hydrophobicity, organic fouling occurs when the membrane is operated in liquid phase. In this study, fabrication method of porous poly(ethersulfone) microfiltration membrane using vapor-induced phase separation and hydrophilic modification of the surface were described. The pore size of microfiltration membrane was optimized by controlling the composition of the dope solution and the vapor exposure time. By combining non-solventinduced phase separation and vapor-induced phase separation, symmetric and asymmetric structure membranes were prepared and their properties were compared. The membrane prepared by the vapor-induced phase separation method had high water permeability and mechanical strength. The fouling resistance of the membrane was improved by surface modification using atom transfer radical polymerization of hydrophilic molecules.