The aim of the study was to investigate the effect of black soybean (BS) on the susceptibility of low-density lipoprotein (LDL) in hypercholesterolemic New Zealand white rabbits. Effects of the BS extract (BSE) and its components on monocyte adhesion of human aortic endothelial cells (HAECs), and adhesion molecule were investigated. Rabbits were divided into four groups, including control, 0.5% cholesterol with 20% casein (either with or without 0.5% vitamin E), and BS groups, all fed for 8 weeks. LDL was treated with 10 μM Cu2+ in vitro to determine the LDL lag time, and the vitamin E content of LDL was determined. The thickness of the tunica intima was measured on paraffin sections of thoracic aortas and aortic arches stained with Movat’s pentachrome. HAECs were pretreated with 100 μg/ml of BSE, and 10 μM of genistein, daidzein, cyanidin, and aspirin for 18 h, followed by tumor necrosis factor (TNF)-α (2 ng/ml) for 6 h, after which U937 cell adhesion was determined. Adhesion molecule expression was examined using ELISAs. The LDL lag time in the BS group was similar to that in the vitamin E group, while its lag time was significantly longer than those in the control and casein groups. The ratio of the intimal area/medial area of the aortic arch of the casein group was significantly higher than those in the control, BS, and vitamin E groups. The vitamin E group had the lowest value, and was closest to the control group. The BS group exhibited a significantly decreased atheroma region in the aortic arch compared to the casein group. Pre-incubation with BSE, genistein, daidzein, cyanidin, and aspirin significantly decreased adhesion by U937 monocytic cells to TNF-α stimulated HAECs. Genistein, daidzein, cyanidin, and aspirin significantly suppressed the expression of vascular cell adhesion molecule (VCAM)-1. Only genistein and aspirin significantly decreased intracellular adhesion molecule (ICAM)-1 expression compared to TNF-α treatment, while no treatments had any effect on E-selectin expression. BS significantly prolonged the LDL lag time and decreased the atheroma region of the aortic arch in hypercholesterolemic rabbits, thereby exerting an antiatherosclerotic effect. Presumably, the BSE downregulate intracellular redox-dependent signaling pathways in HAECs upon TNF-α stimulation through regulating NF-κB, thereby attenuating the inflammatory response in atherosclerosis. The antiatherogenic and anti-inflammatory effects of BS can be used as a nutraceutical for atherogenesis prevention.