PROBLEM TO BE SOLVED: To provide novel cosmetic agents for skin moisture retention having a skin moisture retention effect, and to provide cosmetic compositions for skin moisture retention containing the cosmetic agents for skin moisture retention.SOLUTION: A cosmetic agent for skin moisture retention consists of 4-decyloxazolidine-2-one. The cosmetic composition for skin moisture retention is in the emulsion form having a fat phase, wherein the 4-decyloxazolidine-2-one is included in the fat phase. The emulsion has a neutralized aqueous phase, the aqueous phase is neutralized by the addition of a sodium hydroxide solution, and the fat phase preferably contains 14.5% by weight of hydrogenated polyisobutene.SELECTED DRAWING: None【課題】皮膚保湿効果を有する新規な皮膚保湿用化粧剤、及び該皮膚保湿用化粧剤を含有する皮膚保湿用化粧品組成物の提供。【解決手段】４－デシルオキサゾリジン－２－オンからなる皮膚保湿用化粧剤。脂肪相を有するエマルジョンの形態であり、該４－デシルオキサゾリジン－２－オンは該脂肪相に含まれる、皮膚保湿用化粧品組成物。該エマルジョンは、中和された水相を有し、該水相は、水酸化ナトリウム溶液の添加によって中和されたものであり、該脂肪相は水添ポリイソブテンを１４．５重量％含むことが好ましい。【選択図】なし
