This study was carried out to investigate the effect of CaCO₃ on the Chungkook-jang Meju fermentation. B. subtilis was cultured on the Meju added 0, 0.01, 0.1, 1% CaCO₃, respectively, and the chemical composition, protease activity, amino acid and vitamin B complex were examined with fermentation time. The inner temperature of the CaCO₃ treatments during fermentation was increased as compared with the control group. Titratable acidity in Meju decreased as CaCO₃ cocentration increased. And protease activity and amino-nitrogen content were however high in same order. The content of amino acid was on the increase in every treatments, it made no difference between CaCO₃, treatments and the control. Vitamin B complex content in the CaCO₃ treatments was increased than in the control. The 0.01% added treatment showed the highest amount of vitamin B complex content in all the treatments.