The present application is an invention for a technique which utilizes a soybean block fermenting process for promoting the activation of microorganisms by fermenting soybeans under a far-infrared radiating condition inside a red-clay house and which is capable of preventing discoloration and improving astringency by adding Smilax china L. root extract, jujube extract, and white yam powder when producing the soybean sauce with fermented soybean blocks. The soybean sauce provided in the present application is obtained by a first step of obtaining fermented soybean blocks by producing soybean blocks weighted 3-4 Kg in the usual manner and fermenting/ripening the soybean blocks in a red-clay fermentation room within a temperature range of 35-55 °；C for 30-45 days； a second step of obtaining the Smilax china L. root extract concentrated by heating roots of Smilax china L. and Smilax china L. with 5-10 times of purified water based on the weight of the roots and Smilax china L. after cleaning the roots of Smilax china L. and Smilax china L.； a third step of crushing the 14-16 fermented soybean blocks weighted 3-4 kg and obtained through the first step into a mixing container, adding and kneading/mixing the crushed fermented soybean blocks, 25-35 kg of sun-dried salt, 0.3-1 kg of charcoal, and 18-25 liters of the Smilax china L. root extract obtained through the second step in respect to 100 kg of the soybean sauce, and separating the a soy sauce after fermenting the mixed paste for 3-5 months inside into a soybean sauce container； and a fourth step of adding and kneading/mixing 2-5 liters of the Smilax china L. root extract, 2-5 liters of the jujube extract, and 1-3 kg of white yam powder with respect to 50 kg of the soybean sauce paste from which the soy sauce is separated in the third step, and fermenting the mixed paste for 15-30 days.본원은 메주콩을 발효시킬 때 황토 집에서 원적외선 조사 분위기에서 발효시킴으로 미생물들의 활성화를 도모하는 메주발효공정을 이용하고, 메주로 된장을 담글 때 청미래덩굴뿌리 추출액(맹가액)과 대추추출액 및 산마 가루를 넣어주는 수단으로 갈변
