In this paper, a novel method for evaluating antioxidant activity against low density lipoprotein (LDL) oxidation (anti-LDLox) using a carbon nanotube (CNT) based electrode was investigated. Although ORAC and DPPH are known methods to evaluate antioxidant activity, they do not directly reflect the capacities of anti-LDLox. A method has been reported for measuring oxidized LDL using a CNT electrode. We evaluated anti-LDLox by measuring the amount of oxidized LDL using the electrode after incubation of LDL with antioxidants during copper-mediated oxidation. Thiobarbituric acid reactive substances (TBARS) were also determined for comparison with the CNT electrode. There was a correlation of the CNT electrode with the TBARS and the ORAC, whereas no correlation was found between the CNT electrode and the DPPH. We demonstrate here that a CNT electrode method has a potential for the determination of the antioxidant activity of various natural and synthetic compounds by detecting oxidized LDL.