A new complete blocking filtration model, based on a conventional Hermans-Bredee equation, was presented by introducing two parameters of a specific blocking area A(b), defined by the ratio of blocking pore area to projected area of unit particle and a specific blocking pore number n(b), defined by the number of pores blocked by unit particle. These two parameters were correlated to the membrane structure, the pore size and the particle size. The following results were obtained from filtration experiments with very dilute latex suspension, using five different types of microporous membranes: (1) the physical meanings of A(b) and n(b) were correlated to the membrane structures and the pore density, (2) the relationship between n(b) and A(b) was obtained, and (3) the maximum filtrable particle number was estimated from the values of A(b) and surface porosity of membrane, A(p).