Trachelospermi caulis is used widely as an herbal medicine in oriental countries to attenuate fever and pain. We wished to reveal the novel function of this herb and its active component on barrier function in intestinal epithelial cells. Monolayers of intestinal epithelial cells (Caco-2) were used to evaluate the transepithelial electrical resistance (TEER) and quantity of permeated ovalbumin (OVA) as indices of barrier function. T. caulis increased TEER values on cell monolayers and decreased OVA permeation across cell monolayers. To ascertain the active component of T. caulis, the extract was isolated to five fractions, and the effect of each of these fractions on intestinal barrier function examined. Chloroform and ethyl acetate fractions showed increased TEER values and decreased OVA flux. Chloroform and ethyl acetate fractions contained mainly trachelogenin and its glycoside, tracheloside. Trachelogenin increased TEER values and decreased OVA flux by enhancing the tight-junction protein occludin (but not tracheloside) in Caco-2 monolayers. These findings demonstrated that trachelogenin, an active component of T. caulis, might help to attenuate food allergy or inflammatory bowel disease through inhibition of allergen permeation or enhancement of the intestinal barrier.