Phytochemical constituents were isolated from the seeds of tartary buckwheat (Fagopyrum tataricum) by open column chromatography. Their structures were elucidated as ${eta}$-sitosterol (1), ${eta}$-sitosterol-3-O-glucoside (2), oleanolic acid (3), kaempferol (4), quercetin (5), kaempferol-3-O-rutinoside (6), and quercetin-3-O-rutinoside (7) on the basis of spectroscopic analysis including $^1H$-, $^{13}C$-NMR, and MS. To our knowledge, oleanolic acid (3) has been isolated for the first time from the seeds of Fagopyrum species. The total contents of compounds 4 - 7 were 0.500 mg/g in Daesan maemil, 0.312 mg/g in Yangjul maemil, and 2.185 mg/g in tartary buckwheat.