Odours from animal manure have been of a significant problem in environmental pollutions. Various ways of treating livestock manure have been applied in commercial sectors. Many species of microorganisms are being used but their efficiencies for odour reduction have not been much satisfactory. In this study, Pseudomonas sp. is screened from the fermented soybeans, which is one of the major ingredients of traditional Korea food. Among livestock manures, pig manure is a major source of environmental pollutions more than any other livestock manure. The optimum conditions of culture medium for microorganisms were also studied and found glucose (anhydride) 1.2% (w/v) plus yeast extract 0.6% (v/v). The cultivation of the microorganisms of interest in this study was maximized when cultured for 72 hrs at 28^oC, showing pH of 0.6. The effect of Pseudomonas sp. on reduction of NH₃ from pig manure was found highly significant. The strain of Pseudomonas sp. used was JGJ-1. The characteristics of JGJ-1 were identified by its physiological characteristics as well as its effect on odour reduction from pig manure.