The purpose of this study was to evaluate the quality characteristics and antioxidant activity of chocolate added with Rehmannia Radix Preparata (R. Radix Preparata) concentrate (0, 3, 6 and 9%). As the amount of R. Radix Preparata concentrate increased, water content significantly. The pH of chocolate decreased significantly as R. Radix Preparata concentrate increased, but the acidity of chocolate increased. Sugar concentration and reducing sugar contents also increased according to the amount of R. Radix Preparata concentrate. The L(lightness), a(redness) and b(yellowness) values significantly decreased as R. Radix Preparata concentrate increased. However, texture was not significantly different among the treatments. As the amount of R. Radix Preparata concentrate increased, DPPH radical scavenging and hydroxyl radical scavenging activities increased. In the results of the sensory evaluation, scores of color, taste, flavor, texture, and overall acceptability were the highest in chocolate added with 6% R. Radix Preparata concentrate. From these results, it was suggested that the optimum addition amount of R. Radix Preparata concentrate to chocolate is 6%.