In this study, we verified the effectiveness of ω3 fatty acid ingestion against the pathogenesis of atherosclerosis, and showed that the EPA metabolite 12-hydroxyeicosapentaenoic acid (12-HEPE) suppresses the development of atherosclerosis as an active metabolite that inhibits the transformation of macrophages into foam cells in a peroxisome proliferator-activated receptor (PPAR)γ-dependent manner. Here, PPARG is linked to atherosclerosis.