The present disclosure relates to a cosmetic composition, and more specifically to a cosmetic composition for skin moisturization. The composition contains, as an active ingredient, a composite seawater extract obtained by mixing each of seawater extracts of Brussels sprouts, lima beans, and artichokes. The composite extract extracted from vegetables of Brussels sprouts, lima beans and artichokes by a natural method using seawater has excellent skin water loss-preventing and skin barrier-enhancing effects, and superior skin moisturizing ability. Therefore, the cosmetic composition containing the composite extract, as an active ingredient, can be advantageously used as a cosmetic material having excellent skin moisturizing ability.