A cosmetic composition effective in skin lightening or skin rejuvenation is provided. The cosmetic composition is characterized by containing sodium ions, potassium ions, calcium ions, magnesium ions, chlorine ions and HCO.sub.3 ions in a molar concentration proportion equal to that in the extracellular fluid of mammals and further containing glucose in a concentration of 0.05 to 0.15 mol/L and sodium glutamate in a concentration of 0.01 to 0.03 mol/L.