The living cells, Saccharomyces cerevisiae, are sandwiched between ultrafiltration and reverse osmosis membranes. The ultrafiltration membrane separates the cells from the feed volume, while providing free passage for all nutrients to the cell mass below. Therein, the bioreaction starts to occur, leading to product ethanol. The reverse osmosis membrane, while immobilizing cells, also helps in separating the nutrients from the product stream preferentially. Therefor, the enriched ethanol solution could be obtained without much contamination from glucose and nutrients. Above the filtered cell mass a coarse filter paper was placed to provide the cells extra room for growth and to eliminate the partial closing of pores of the ultrafiltration membrane which is in contact with the cells. In order to minimize the back diffusion of ethanol from the yeast cell layer to the feed solution, the cellulose acetate ultrafiltration membrane was replaced into the more hydrophobic polysulfone ultrafiltration membrane. In these cases, performance data for glucose fermentation to ethanol by yeast cells were obtained. As a result, the maximum ethanol concentration was 70.3g/l after 400 hours of operation continuously and at the operating pressure of 2758 kPa(=400psig)on the substrate solution for the forced convection flow of substrate to the cell layer.