Microstructure of anode strongly influences the overpotential characteristics and the best microstructure depends on the anode materials and the operation conditions. Because the experimental optimization of microstructure requires a number of trials and errors, the development of a simulation approach that supports optimizing the anode microstructure is of great importance. In this study, we present a new simulation method; a three-dimensional porous structure simulator for optimizing the microstructure of porous anode. The developed method supports quantitative evaluations of microstructure, cross-sectional areas, triple-phase boundary, etc. We applied the developed method to Ni-YSZ cermet anode for SOFC Electrical properties and overpotential characteristics were calculated for cermet anodes with different microstructure. Quantitative estimation of overpotential for Ni-YSZ cermet anode with different microstructure was obtained.