A steroidal saponin, $3-O-{alpha}-L-rhamnopyranosyl-(1{ ightarrow}2)-[{alpha}-L-rhamnopyranosyl-(1{ ightarrow}3)]-{eta}-D-glucopyranosylpennogenin$ ;(1, spiroconazole A) was isolated from the tubers of Dioscorea bulbifera L. var sativa and $^1H-and;^{13}C-NMR$ assignment was completed using HMBC correlation. In addition, four phenolic substances, 2,7-dihydroxy-4-methoxyphenanthrene (2), quercetin (3), $quercetin-3-O-{eta}-D-glucopyranoside$ (4), and $quercetin-3-O-{eta}-D-galactopyranoside$ (5) were also isolated.