A new type of photocatalytic reaction system, in which filtration and a photocatalytic reaction occur simultaneously, is reported. The concentration of trichloroethylene (TCE) in permeate stream decreased by approximately 5 ppm while TCE permeating porous TiO2 membranes under conditions of blacklight irradiation. In addition, membrane fouling by polyethyleneimine, which caused a decrease in permeate flux, was also found to be reduced by photocatalytic reaction.