The present invention relates to: an agent for inhibiting or improving the decrease of loricrin in a cornified envelope of a horny cell layer of the skin, a transglutaminase-3 activator, and an agent for promoting the formation of a cornified envelope of a horny cell layer of the skin or for strengthening the structure of a cornified envelope of a horny cell layer of the skin, each of which contains sphingomyelin as an active ingredient； a composition； and a food or beverage. According to the present invention, it becomes possible to inhibit or improve the decrease of loricrin in a cornified envelope of a horny cell layer of the skin, and it also becomes possible to activate transglutaminase-3 in a cornified envelope of a horny cell layer of the skin. Therefore, it becomes possible to promote the formation of a cornified envelope of a horny cell layer of the skin and strengthen the structure of a cornified envelope of a horny cell layer of the skin. Due to these effects, the deterioration of a barrier function of skin can be prevented, inhibited or improved in a safe, simple and economically advantageous manner.本發明係關於以鞘磷脂(Sphingomyelin)作為有效成分之皮膚角質層角化肥厚膜之兜甲蛋白減少之抑制/改善劑、轉麩胺醯胺酶3活化劑及皮膚角質層角化肥厚膜之形成促進/構造強化劑、組成物及飲食品。依據本發明，可抑制或改善皮膚角質層角化肥厚膜之兜甲蛋白之減少，且可實現皮膚角質層角化肥厚膜之轉麩胺醯胺酶3之活化化，進而藉此可實現促進、構造強化皮膚角質層角化肥厚膜之形成。而且藉由該等作用，可安全且簡易地經濟地預防、抑制或改善皮膚之障蔽功能降低。
