The transdermal delivery of cosmetic ingredients is often resisted by the outer layer of the skin, which can prevent diffusion of cosmetic ingredients through the skin. Ethosomes, lipid carriers composed mainly of phospholipids and ethanol, are one of the methods used to overcome the limitation of the skin barrier for cosmetic ingredients. We prepared ethosomes containing Rhodamine B (Rh-B) and investigated the correlation between the synthesis conditions of ethosomes and ethosome size and entrapment efficiency of Rh-B within the ethosome. Based on the correlation results, we examined the effect of ethosome size and entrapment efficiency of Rh-B within the ethosome on skin permeation of Rh-B. The skin permeability of Rh-B increased as ethosome size decreased and entrapment efficiency of Rh-B increased. Finally, the Rh-B or niacinamide loaded within ethosomes showed significantly higher skin permeation. The results indicated that using ethosomes can improve the skin permeability of niacinamide, and the same effect can be expected for other cosmetic ingredients.