Catechin-7-O-${eta}$-D-glucopyranoside (CA-G) was previously isolated from red bean (the seed of Phaseolus calcaratus cv. Roxburgh). This study examined the ability of CA-G to scavenge reactive oxygen species generated by cell-free systems and to protect cells from oxidative stress caused by hydrogen peroxide ($H_2O_2$). The mechanism by which CA-G exerts its antioxidant and anti-apoptotic action on $H_2O_2$-exposed cells was also investigated. CA-G treatment prevented $H_2O_2$-mediated apoptosis and inhibited the formation of single stand breaks in DNA in $H_2O_2$-exposed BJAB cells. CA-G suppressed mitochondrial stress and caspase activation caused by $H_2O_2$. Mechanistic experiments revealed that the antioxidant mechanism of CA-G on $H_2O_2$-mediated oxidative damage was due to the direct scavenging of hydroxyl radicals and/or to the chelation of metal ions that were used to produce hydroxyl radicals from $H_2O_2$ via the Fenton reaction. Collectively, these findings suggest beneficial roles of CA-G or CA-Grich red bean on the protection from oxidative damage.