The Dongchimi added with Wasabi (Wasabia japonica Matsum) for the improvement of quality was scientifically explored by reviewing the optimum level and its effect on the microbiological and sensory characteristics of product fermentation. The final weight percentage of Wasabi in Dongchimi was adjusted to 0, 3, 5, 7 and 9%, per radish, respectively. Microbiological and sensory characteristics were determined during fermentation at $10^{circ}C$ for 55 days. The viable cell counts of total and lactic acid bacteria had increased to their maximum values during fermentation until they began to drop at the later stage. Here, the 7% treatment showed a distinctive low and high numbers of total cells and lactic acid bacteria, respectively, during the later stage of fermentation. As for the sensory evaluation results of the fermented Donchimi with Wasabi, the 7% treatment was most favored for the color, the smell, the sour taste, the hot taste, the carbonated taste, the texture, and the overall acceptability of the products. The optimum levels of Wasabi in Dongchimi were estimated between 5 and 7% per added radish weight, and the 7% level was more preferred when the fermentation-retarding effect of the product was considered.