Membrane process has been employed to separate a specific substance from gas or liquid mixture, and treat wastewater. This is due to the fact that the substance of mixture can be permeated and separated selectively by membrane. Since initial equipment and operation costs are not expensive, membrane process has been adopted in various fields such as petroleum industry, chemistry, polymer, electronics, foods, biochemical industry and wastewater treatment. In this study, CaCO₃ particles impregnated in silicone rubber network were extracted by using supercritical carbon dioxide and pore distribution of silicone rubber-CaCO₃ was investigated with varying amount of extract. Silicone rubber has excellent mechanical properties such as heat-resistance, cold-resistance etc, and CaCO₃ has microporous structure. It is possible to make silicone rubber-CaCO₃ composite sheets via work-intensive kneading processes. In so doing CaCO₃ particles become distributed and impregnated in silicone rubber network. Supercritical carbon dioxide diffuse through composite sample, then sample is swollen. CaCO₃ in silicone rubber network is dissolved in supercritical carbon dioxide, and its sites become pores. Pore distribution, pore shape and surface area are observed by SEM(scanning electron microscope) micrograph and BET surface area analyzer examination respectively. fore characteristics of membrane suggest the possibilities that the membrane can be used for process of mixture separation and wastewater treatment.