Leucaena leucocephala was one of Mimosaceae family which had high protein content nearly the same value as in Soya beans protein content. L. leucocephala could be used as the substitution of Soya beans in production of soy sauce. Soy sauce was one of fermentation liquid products which had flavor and aroma as meat, and had high nutrition value. The aims of the research were (i) to analyze nutrition value in seeds, koji and moromi including carbohydrate, proteins and lipids and (ii) to know the potency of L. leucocephala as raw material in production of soy sauce by fermentation method with Aspergillus oryzae as inoculums. Fermentation was one of soy sauce production processes that involved two steps: (i) the solid stage fermentation and (ii) the brine fermentation. L. leucocephala was fermented with A. oryzae for 3-5 days to produce koji. Koji was soaked in salt solution 20% (1:5 b/v) then it was fermented for 30 days to produce moromi. Nutritional values in L. leucocephala seeds, koji, and moromi was analyzed, i.e. carbohydrate (sugar reduction and starch), protein, and lipids. Moromi filtrate was added by spices to Leucaena sauce. Finally, preferable Leucaena sauce was tested including flavor, aroma, and color. Preferable data was analyzed by non-parametric statistic; it was Friedman Test and followed Wilcoxon Ranking Method. The result showed that value of reducing sugar in L. leucocephala seeds, koji and moromi were 78.38 mg/g; 119.08 mg/g; and 164.29 mg/g. Starch value of seeds, koji and moromi were 274.36 mg/g; 260.92 mg/g and 179.50 mg/g. The value of dissolved protein in seeds, koji and moromi were 107.44 mg/g; 86.1 mg/g; and 208.56 mg/g. The value of lipids on seeds, koji and moromi was 158.87 mg/g; 51.35 mg/g; and 80.86 mg/g. The data of preferable test on Leucaena sauce’s taste was the same as ABC sauce but the aroma of Leucaena sauce had the lowest score than the others. More over, the four kinds of sauce were not different significantly in color. L. leucocephala had potency as raw material in production of soy sauce by fermentation method with A. oryzae as inoculum. Keywords: Leucaena leucocephala, soy sauce, Aspergillus oryzae.