Total phenolics and antioxidant activities of water and 80% methanol extract of chestnut inner skin were investigated. The antioxidant properties of both extracts of chestnut inner skin were evaluated using different antioxidant tests, including 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical scavenging activities, reducing power, ferric reducing ability of plasma (FRAP), and inhibitory effects on ${eta}$-carotene bleaching. The 80% methanol extract of inner skin exhibited the higher DPPH, ABTS radical scavenging activities, reducing power, and FRAP than water extract of inner skin and did also in a concentration-dependent manner. However, inhibitory effects on ${eta}$-carotene bleaching of 80% methanol extract was similar to those of water extract, 35.09 and 39.07% at 1 mg/mL, respectively. The total phenolic contents of water and 80% methanol extract from chestnut inner skin were 5,801.42 and 9,735.56 mg/100 g, respectively. High performance liquid chromatography (HPLC) analysis showed that gallic acid was the predominant phenolic compound in water and 80% methanol extract from inner skin. These water and 80% methanol extracts of chestnut inner skin can be utilized as an effective and safe source of antioxidants.