For the filtration of super compactible cake, the high filtration pressure can not improve filtration rate. As the high pressure, in this case, decreases the cake porosity adjacent to filter medium and thus forms 'dense skin' which decreases the rate of liquid flow in a great extent. Actually, there was no method to improve filtration rate for the filtration with super compactible cake. We propose the saturation of CO2 gas into the suspension before the filtration operation for improving the filtration rate. The dissolved CO2 gas transforms itself into gas phase in the dense skin through which the pressure changes dramatically. The gas secures its space inside the dense skin, and finally forms the flow passages which improve the filtration rate.