Jungkwa is a traditional Korean dessert preserved in honey or sucrose. This study was carried out to investigate the antioxidant activities and quality characteristics of Rehmannia glutinosa Jungkwa (RJ). RJ was prepared after six repeated cycles of boiling-cooling. After blanching fresh Rehmannia glutinosa (600 g) for 5 min at $100^{circ}C$, Rehmannia glutinosa was boiled in sucrose syrup (sucrose 720 g in water 600 g) for 60 min and then cooled for 24 hr. Moisture, pH and color values of lightness, redness and yellowness in the Hunter color system of Jungkwa decreased as the number of boiling-cooling cycles increased, whereas acidity, $^{circ}Brix$ and reducing sugar contents of syrup increased. Total phenol content increased in by the 6th boiling-cooling cycle. Antioxidant activities, including DPPH and hydroxyl radical scavenging activities, increased in RJ by the 6th boiling-cooling cycle. Based on these results, the antioxidant activities of Rehmannia radix Jungkwa was improved according to an increasing number of boiling-cooling cycles due to increased total phenol contents.