PROBLEM TO BE SOLVED: To provide a hair dying agent and a hair dying method having excellent hair-dyeing properties and causing less coloration of skin.SOLUTION: A hair dying agent comprises: a first agent comprising a material which reacts with iron to develop a color, and a compound represented by the following formula 1 of 0.1 mass%-12 mass% relative to the total mass of the first agent； and a second agent comprising iron salt, where X-Xindependently represent a single bond or a hydrophilic group, where, at least one of X-Xis a hydrophilic group.SELECTED DRAWING: None【課題】染毛性が良くかつ皮膚着色の少ない染毛剤及び染毛方法を提供すること。【解決手段】鉄と反応して発色する物質、及び第１剤の全質量に対して０．１質量％～１２質量％の下記式１で示される化合物を含む第１剤；並びに鉄塩を含む第２剤；を含む染毛剤。【化１】式中、Ｘ１～Ｘ４はそれぞれ独立に単結合又は親水性基を示し、但し、Ｘ１～Ｘ４のうち少なくとも１以上は親水性基を示す。【選択図】なし
