Atherosclerosis is driven by inflammation, with a strong involvement of innate immunity, and involves an expansion of the arterial intima, a normally small area composed of several cell types including smooth muscle cells, lipids, monocytes, macrophages, dendritic cells, and extracellular matrix. Macrophages derived from recruited monocytes are predominant innate immune cells that play crucial roles in the formation of atherosclerotic lesions. Human atherosclerotic plaques have shown that macrophage subsets within a plaque might be more useful for explaining plaque phenotype than just simply giving the total number of macrophages. Therefore, recognizing the roles of macrophage subsets in atherosclerotic plaque formation, progression, and regression would be most helpful for identification of novel strategies to stabilize, or attenuate atherosclerotic lesions. This review discusses the impact of macrophage subsets and their roles in atherosclerosis.