sources of flavonoid, including quercetin, rutin and catechin. The flavonoid content of Tartary buckwheat is 9 - 300 times higher than the common buckwheat. The objective of this study was to compare phenolic compound content and antioxidant activity of tatary buckwheat and common buckwheat in different plant parts. Methods and Results : Total polyphenol, flavonoid contents and DPPH free radical scavenging activity was measured in seed, stem and leaf of tatary buckwheat followed by cultivation period. Total polyphenol content was higher in tatary buckwheat compared to common buckwheat. Total polyphenol contents was 347.33 ㎍/㎖ in tatary buckwheat seed extract and 57.24 ㎍/㎖ in common buckwheat stem (2 month). Total flavonoid content was also higher in tatary buckwheat than common buckwheat. Total flavonoid contents of tatary buckwheat seed extract was 45.68 ㎍/㎖, where as common buckwheat seed content 21.29 ㎍/㎖. DPPH free radical scavenging activity was higher in tatary buckwheat than common buckwheat. DPPH free radical scavenging activity was 85.76% in tatary buckwheat leaf (2 month) and 54.44% was in common buckwheat stem (2 month). Conclusion : This study indicates that polyphenol contents of tatary buckwheat extract depend on their part and the chronology is the seed> leaf > stem. Total polyphenol and flavonoid contents of leaf and stem is in inverse proportion to cultivation period. But, DPPH free radical scavenging activity make no difference according to plant cultivation age.