Microporous membranes were prepared by the paste method. Certain properties of the resultant microporous membranes such as porosity, pore size, specific surface area, and N-2 gas permeability were estimated. Furthermore, the membrane structure was observed with the aid of scanning electron microscopy. It was elucidated that the membranes consist of aggregates of minute spherical particles, made up of poly(styrene-divinylbenzene) with micropores.