NOVELTY - Preparing an organic fertilizer comprises crushing an organic manure in a manure storage tank and stirring it with water, using probiotic spray treatment to break down sewage and odor components in the storage tank, mixing and crushing the crushed manure, applying heat by using a heat exchanger, stirring the heat treated mixed manure with water in a fermentation tank at a constant temperature, hot air drying the treated fermented sewage water to adjust the moisture content, performing plastic molding process to prepare solid fertilizers in the fermentation tanks.    USE - The method is useful for preparing an organic fertilizer (claimed) from human excrement or livestock excretion.    ADVANTAGE - The organic fertilizer can reduce soil contamination and water pollution in human excrement or livestock excretion, and can prevent bad smell component by injecting the microorganism composition in the stirring process.    DETAILED DESCRIPTION - Preparing an organic fertilizer comprises crushing an organic manure in a manure storage tank and stirring it with water, using probiotic spray treatment to break down sewage and odor components in the storage tank, mixing and crushing the crushed manure, applying heat by using a heat exchanger, stirring the heat treated mixed manure with water in a fermentation tank at a constant temperature, hot air drying the treated fermented sewage water to adjust the moisture content, performing plastic molding process to prepare solid fertilizers in the fermentation tanks, performing odor abatement process to decompose and deodorize odors of the fermented manure in the fermentation tank, performing the moisture control process and the hot-air drying process again in the sewage water so that the water content is reduced to 20-30 %, cooling the dried manure by ambient drying process so that the water content in the manure is reduced to 5-10%, where a first odor reduction process and a second odor reduction process used in robotics with organic acids have a pH of 2-4.