In coagulation-membrane hybrid processes filtrating coagulated suspension without removing coagulated flocs, permeability of cake formed by accumulation of the flocs may have great influence on the efficiency of the entire process. Therefore we have investigated the physical properties of the cake formed from coagulated flocs in terms of floc size and fractal dimension, and developed a model based on fractal theory with considering cake collapse under filtration pressure to predict the porosity and permeability of the cake. We performed experiments using a batch filtration device and a confocal laser scanning microscope (CLSM) to verify the predicted specific cake resistances (which is reversely proportional to cake permeability) and porosities under various conditions. The calculated porosities and specific cake resistances of the collapsed cakes were in reasonably good agreement with those obtained experimentally. From the model calculations, it was found that the specific cake resistance decreases upon increasing the aggregate size and decreasing the fractal dimensions.