The purpose of this study was to determine the content of polyphenols and flavonoids, vitamin C, and antioxidant activity for the extract from the Deodeok sprout. To accomplish this, the Deodeok sprout whole (CLS-W), above ground part (leaf, stem, CLS-L), and root (CLS-R) were individually extracted using 70% ethanol. The highest levels of total polyphenols and total flavonoids were observed in the Deodeok sprout extract CLS-L2. Similarly, antioxidant activities resulting in radical scavenging activities increased significantly in the extract of CLS-L2. In conclusion, these results indicate that Deodeok sprouts can be used as a viable, new natural antioxidant source.