A method for successively performing hair dyeing and hair straightening, the method including the steps of: performing dyeing on hair； applying, to the hair immediately after being subjected to dyeing, a reducing first agent containing a basic dye and/or an HC dye, and leaving the hair for a certain time, thereby performing reduction on cystine bonds； shaping the hair that has been subjected to reduction into a straight configuration； and applying an oxidizing second agent to the hair that has been shaped into a straight configuration, and leaving the hair for a certain time, thereby performing oxidation for reforming the cystine bonds.
