Al foams with high porosity were fabricated via melt foaming method. In this process, Ca and TiH2 are used as thickening and foaming agent. The macrostructure of aluminum foams exhibited homogeneous distribution of fine pore sizes at shorter holding time. From comparison of the actual pore sizes with ones calculated with modified Ostwald ripening, the measured pore sizes were well fitted to the calculated ones. These results suggest that hydrogen diffusion through pore walls from smaller pores to a larger one is the main process of pore evolution at least in the later period of holding. The detailed are discussed in the context.