We studied the antioxidant activities and quality characteristics of gelatin jelly prepared with different amounts (0%, 0.25%, 0.50%, and 0.75%) of Rehmannia Radix Preparata (RRP) concentrate. The moisture content of the control group was 61.62%, and the acidity and pH were 3.68 and 1.96%, respectively. The reducing sugar content of the jellies ranged from 10.83% to 13.1% (from 35.0 $^{circ}Brix$ to 37.0 $^{circ}Brix$). The acidity of the control group was the lowest, followed in order by the 0.25% RRP, 0.50% RRP, and 0.75% RRP groups. The lightness, redness, and yellowness of the Hunter color system decreased with increasing RRP concentrate, whereas the hardness, cohesiveness, and springiness increased with increasing concentrate. The total phenol content was the highest in 0.75%. Antioxidant activities such as DPPH radical scavenging and hydroxyl radical scavenging were the highest with the 0.75% group ($IC_{50}$ value of DPPH radical scavenging activity: 85.42 mg/mL for 0.75%, 484.25 mg/mL for control; $IC_{50}$ value of hydroxyl radical scavenging activity: 54.42 mg/mL for 0.75%, 135.54 mg/mL for control). The sensory evaluation results showed that overall preference and texture were the highest in the 5% addition group. From these results, it was suggested that the optimum amount of RRP concentrate to add to jelly is 0.50%.