PURPOSE: To form functional ceramics by culturing a microorganism capable of forming an antioxidant substance, mixing the culture solution of the microorganism with clay, burning the mixture at a specific temperature.

CONSTITUTION: One or more microorganisms capable of forming an antioxidant substance such as an actinomyces, e.g. Streptomyces sp., a photosynthetic bacterium, e.g. Rhodopseudomonas sp., a lactic acid bacterium, e.g. Lactobacillus sp., a filamentous fungus such as Aspergillus sp. and yeast, e.g. Saccharomyces sp., are cultured in about 4% solution of molasses at pH3.10-4.5. Then, the culture solution is mixed with clay or a binder similar to clay, burnt at ≥500°C to give powdery or granular functional ceramics. The ceramics are usable for promoting growth of plant, cleaning dirty water and reducing an offensive smell.