The Nagano Purple grape (Vitis (V.) viniferaxV. labrusca) is a hybrid created by a cross between Kyoho (V. viniferaxV. labrusca) and Rosario Bianco (V. vinifera) grapes. The grape, including its skin, can be eaten and contains no seeds because of gibberellin treatment. The skins of various fruits have been shown to contain antioxidant activity. However, it is unclear whether the Nagano Purple grape contains antioxidant activity. We prepared the skins and dried fruits (including the skins) of the Nagano Purple grape, so as to assay for the presence of an antioxidant activity. We examined the concentration of polyphenols in the grape and further assayed whether components in the grape inhibited the oxidation of low-density lipoprotein (LDL). We detected the presence of cyanidin-3-glucoside (Cy-3-glc), five anthocyanidins and resveratrol in the skins. A trace of resveratrol was detected in the pulp. LDL collected from human subjects 1 h following the consumption of the skins or dried fruits revealed significant inhibition of LDL oxidation compared to that observed in fasting venous blood samples. We further observed the antioxidant activity of Cy-3-glc. Our results suggest that the consumption of the Nagano Purple grape can give rise to resistance to LDL oxidation.