PROBLEM TO BE SOLVED: To provide a therapeutic agent for dermatitis with excellent effectiveness and safety which is not only effective and safe to a dermatitis patient particularly atopic dermatitis, but also remarkably effective to a serious case which is determined to be very intractable by conventional external preparation, is applicable to an affected part such as face and neck and furthermore to a case of sensitive skin, and is applicable to children or women safely, and to provide an external preparation that is effective to skin care cosmetic, and has an improvement effect of skin tension and wrinkles, moisturizing effect, and also a hair restoration effect.SOLUTION: An external skin care preparation composition has C-type natriuretic peptide (CNP) or B-type natriuretic peptide (BNP) as an active ingredient, which is particularly a therapeutic agent for dermatitis or skin quality improvement agent. Furthermore, a cosmetic for skin and scalp contains the peptide.SELECTED DRAWING: None【課題】皮膚炎患者、特にアトピー性皮膚炎に対して有効かつ安全であるばかりでなく、従来の外用剤では非常に難治性と判断される重症例に著効し、顔面、首等の疾患部位への塗布が可能であり、更には、皮膚が敏感な症例、小児や女性にも安心して塗布できる有効性と安全性の優れた皮膚炎治療剤の提供。また、皮膚の肌のハリ、しわの改善、保湿効果を有し、育毛効果もあるスキンケア化粧料に有効な外用剤の提供。【解決手段】Ｃ型ナトリウム利尿ペプチド（ＣＮＰ）またはＢ型ナトリウム利尿ペプチド（ＢＮＰ）を有効成分とする皮膚外用剤組成物、特に、皮膚炎治療剤または肌質改善剤。さらに、前記ペプチドを含む皮膚用および頭皮用化粧料。【選択図】なし
