In order to develop of support media for biofilm reactor, physicochemical properties and attachability of surface of activated carbon, clay mineral, non-clay mineral, and waste mold sand were examined. Measured physicochemical properties of materials were surface roughness, mean particle size, surface area, hydrophobicity, and surface charge. At a tested materials, activated carbon was the best attachable material and microorganisms were attached 20.1 × 10^7 CFU/㎠ at surface, compared with diatomaceous earth which were attached of 9.2 × 10^7 CFU/㎠. In our research, surface area and hydrophobicity showed more influence than any other factor on attachment of microorganisms.