We developed the microbial immobilization particle with curdlan and activated carbon, which has great adsorption capacity. The characteristics of porosity and mechanical strength of these supporting particles are dependent on manufacturing method. The supporting particle showed the best performance when the ratio of curdlan and activated carbon was 30 to 6 g/L. Brumauer-Emmett-Teller (specific surface area) and swelling capacity of the carrier were 52.63 m(2)/ g and 17 (w/w), respectively. The immobilization characteristics of iron-oxidizing bacteria on supporting particles were observed using a scanning electron microscope. The concentration of microorganism on the surface of supporting particle was increased with reaction time. As the number of iron oxidation batch cycles increased, the iron oxidation rate increased.