Modified radish Kimchi and radish-root juice were fermented under $N_2$ atmosphere at $22{sim}23^{circ}C$ and $37^{circ}C$, respectively and their changes of vitamin C content. were determined by dinitrophenylhydrazine and indophenol methods. In the earlier period of the fermentation, vitamin C content decreased temperarily and then began to increase. When the flavor of Kimchi was most acceptable, vitamin C showed the maximum value which eras equivalent to or more than the initial, after which vitamin C content decreased gradually. The increase of vitamin C content seemed to come from the biosynthesis of the vitamin owing to the enzymatic action occurred in radish-root. The addition of galacturonic acid to Kimchi and to radish-root juice elevated the vitamin C content, which suggested galacturonic acid was a good substrate for the synthesis of vitamin C. The optimum pH of the Kimchi fermentation for the better vitamin C content ranged 4.0 to 4.5.