The antitumor activity of the roots extract of Pueraria thunbergiana was investigated on the basis of cytotoxicity upon the cultured human tumor cell lines, in vitro. The purification of methylene chloride (MC) soluble part and ethylacetate (EA) soluble part of extract by column chromatography furnished seven isoflavonoids, two triterpenoids, one but-2-enolide. The structures of them were established by chemical and spectroscopic means to be lupeol (1), $eta$-sitosterol (2), biochanin A (3), (-)-tuberosin (4), calycosin (5), daidzein (6), puerarin (7), daidzin (8), (+)-puerol-B 2-O-$eta$-glucopyranoside (9), formononetin-7-O-$eta$-glucopyranoside (10). Each isolates ($1{sim}10$) were evaluated for inhibitory activities on the proliferation of cultured human tumor cell lines such as A549, SK-OV-3, HCT-15 and SK-MEL-2, respectively.