The inhibitory effect of the aerial parts of Fagopyrum esculentum on the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical was examined. The n-butanol fraction from the methanol extract of title plant showed stronger inhibitory effect than other fractions on DPPH radical. Two flavonoids were isolated from n-butanol fraction having the potent activity and elucidated as quercetin-3-O-${alpha}$-L-rhamnoside and quercetin-3-O-rutinoside on the basis of spectral evidence. The $IC_{50}$ values of these compounds on DPPH radical were 6.56 ${mu}M$ and 8.37 ${mu}M$, respectively.