Current study investigated phytochemical compositions and antioxidant capacity of Korean leafy vegetables including chajogi, gomchwi, meowi and sseumbagwi. ${eta}$-carotene, total soluble polyphenol, total flavonoids contents were determined, and antioxidant capacity were evaluated by various methods. ${eta}$-carotene, total soluble polyphenol, total flavonoids contents in gomchwi were significantly higher (as much as 19 folds) compare to other vegetables (p<0.05). Sseumbagwi extract ($100{mu}g/mL$) was removed 78.6% of superoxide radicals in xanthin-xanthin oxidase system measured by EPR. Gomchwi showed the highest nitrate scavenging activity as 94.3% at pH 1.2. In SOD-like activity, chajogi, gomchwi, and meowi were evaluated in the range of $12.6{sim}24.5%$. All samples were revealed to prevent the reaction of ferrous chloride during 9 days, which were comparable ability with 125 mg/100 g of ${alpha}$-tocopherol. The rich phytochemical contents of gomchwi and sseumbagwi influenced to high antioxidant capacity.