Five compounds were isolated from the BuOH fraction of Polygonum bistorta (Polygonaceae). On the basis of spectral data, these compounds were established as caffeic acid, quercimeritrin, avicularin, gallic acid and protocatechuic acid. The inhibitory activies on $3{alpha}-hydroxysteroid$ dehydrogenase $(3;{alpha}-HSD)$ of isolated compounds were compared. $IC_{50}$ value of isolated compounds were $133.57;{mu}g/ml;(caffeic;acid)$, $89.1;{mu}g/ml;(quercimeritrin)$, $189.85;{mu}g/ml;(avicularin)$, $140.69;{mu}g/ml;(gallic;acid)$ and $165.27;{mu}g/ml;(protocatechuic;acid)$ respectively. Although all compounds showed lower inhibition activities than BuOH fraction $(IC_{50}<50;{mu}g/ml)$ of Polygonum bistorta, it showed higher inhibition activities than aspirin $(IC_{50};246.81;{mu}g/ml)$.