Compounds of isolated from roots extract of Pueraria thunbergiana were tested their inhibitory effects on $alpha$-glucosidase and $alpha$-amylase. Inhibitory activity of methylene chloride (MC) fraction and ethyl acetate (EA) fraction against $alpha$-glucosidase showed more than 60% at a concentration of $500{mu}g/m{ell}$. Among the nine compounds tested on $alpha$-glucosidase, biochanin A, (-)-tuberosin and calycosin from MC fraction and daidzein from EA fraction were stronger inhibitors than acarbose ($IC_{50}=530{mu}g/m{ell}$), and their $IC_{50}$ were 9, 144, 328 and $20{mu}g/m{ell}$, respectively. Biochanin A and (-)-tuberosin also inhibited $alpha$-amylase activity as like as acarbose $IC_{50}=20.5{mu}g/m{ell}$), and their $IC_{50}$ were 22 and $348{mu}g/m{ell}$, respectively. Although daidzein was already known $alpha$-glucosidase inhibitory effects, it was newly evaluated that biochanin A and (-)-tuberosin inhibited $alpha$-glucosidase as well as $alpha$-amylase, and that calycosin did $alpha$-glucosidase.