As a folkloric medicine, Siegesbeckia pubescens has been used for treatment of brain stroke and hypertension. Diterpene compound, 16,17-dihydroxy 16-${eta}-(-)$ kaurane-19-oic acid, was isolated from the plant. Its potential antihypertensive activity was evaluated againstan animal model of hypertension, Okamoto-SHR. When diterpene compound with dose of 50mg/kg/day was orally administered, it exhibited mild antihypertensive activity comparable with propranolol administration dose of 75mg/kg/day.