To provide a first agent for oxidation hair dyeing by which an adverse effect (roughness of cuticle, for example) to touch of finished hair is reduced more, and which is stable with time, and a novel application method.SOLUTION: A first agent for oxidation hair dyeing contains: (A) nonionic surfactant having at least one kind of HLB12 or less； (B) higher alcohol having at least one kind of liquid-state oil or fat agent and at least one kind of C14 or more； (C) at least one kind of anionic surfactant or at least one kind of ampholytic surfactant； and (D) at least one kind of solvent. Further, there are provided an oxidation hair dyeing agent kit containing the first agent for oxidation hair dyeing, and an application method.SELECTED DRAWING: Figure 3【課題】 仕上がりの毛髪の感触への悪影響（例えばキューティクルの荒れ）がより低減され、経時的に安定な酸化染毛用第１剤及び新規塗布方法を提供すること。【解決手段】 （Ａ）少なくとも１種のＨＬＢ１２以下のノニオン界面活性剤界面活性剤と、（Ｂ）少なくとも１種の液状油脂剤及び少なくとも１種のＣ１４以上を有する高級アルコールと、（Ｃ）少なくとも１種のアニオン界面活性剤又は少なくとも１種の両性界面活性剤と、（Ｄ）少なくとも１種の溶剤を含有する、酸化染毛用第１剤である。又、この酸化染毛用第１剤を含有する、酸化染毛用第１剤及び塗布方法。【選択図】図３
