The present study addresses a numerical method for estimating macroscopic material properties by predicting the time variation of a three-phase porous microstructure, composed of Nickel (Ni) and Gadolinium doped ceria (GDC), due to sintering. The phase-field method (PFM) is applied for simulating the sintering process and the effect of creep deformation of the constituent materials is taken into account by introducing the strain energy to the PF free energy functional. The numerical results show that the temporal changes by sintering of the microstructure decrease the total length of triple phase boundaries and that the strain energy deteriorates the wettability between Ni and GDC more than a little.