The present invention provides a method for dyeing keratin fibers and a keratin fiber dye which have excellent dyeing properties and which result in less damage and irritation to the hair and scalp even when the head hair is dyed. Disclosed are the method for dyeing keratin fibers is disclosed which comprises using an oxidation dye and an oxidase that can oxidize the oxidation dye and under pH conditions where both the oxidase and the keratin fibers are negatively charged, which comprises the step of: before dyeing, treating the keratin fibers with an electrostatic repulsion inhibitor having a property of being positively charged under the pH conditions during the dyeing, and the keratin fiber dye used in the dyeing method.
