The contents of total phenol and total flavonoid of artichoke (Cynara scolymus L.) were measured. The antioxidant activity of the artichoke was evaluated based on its potential as a scavenging the ABTS radical. These results showed the antioxidant activity of artichoke has a close relationship with the total flavonoid content. The compound showing antioxidant activity was isolated from the artichoke by repeated column chromatography and recrystallization. Based on the spectrometric studies, the compound was identified as 1,3-dicaffeoylquinic acid, known as cynarin. The content of cynarin from heads and leafs of the artichoke determined by $C_{18}$ reversed phase HPLC (high-performance liquid chromatography) coupled with photodiode array detector was 10.15 and 0.67 mg/g, respectively. This compound showed potent antioxidant activities against DPPH and ABTS radicals ($EC_{50}$ = 14.09 and 28.85 ${mu}M$, respectively).