Deoduk (Codonopsis lanceolata) root powder was added to traditional kochujang to improve the quality of traditional kochujang. The microbial characteristics, enzyme activities, and sensory characteristics were investigated during fermentation. The aerobic bacterial count in kochujang was not remarkabley different, and yeast and mold decreased during fermentation. Yeast and mold in the kochujang with 3 and 5% added deoduk root powder were 5 log scale at 8 weeks, whereas those in the control reached the same level at 6 weeks. ${alpha}$, ${eta}$-Amylase activity was at its highest level at 4 weeks during fermentation, and glucose and fructose contents showed the same results. The major free sugars in kochujang were glucose and fructose, and their contents increased rapidly at 2 weeks. Free sugar contents of kochujang with added deoduk was higher than that in the control. The sensory evaluation results showed that 1 and 3% deoduk kochujang had higher scores for taste and overall acceptance than those in the control. In particular, 1% deoduk kochujang had the highest scores.