Physical properties of various inorganic materials have been measured in terms of pore size distribution and porosity, BET surface area by nitrogen adsorption, pH, ion conductivity, and concentration of ions after elution test. The microbial survival rate and their stability have been monitored in every 10 days during 120 days by dilution plating method. The correlations between physical property of the inorganic carrier and microbial survival rate have been examined for the better preparation of microbial fertilizer. Average size of pore, and concentration of soluble ions were unequivocal factors affecting on microbial survival rate but BET surface area, average porosity, and ion conductivity revealed the equivocal correlation with microbial survival rate. Higher concentration of soluble ions gives lower survival rate and inorganic carriers with high microbial survival rate seemed to have preferred range of pore size.