A hair treatment method comprising steps 1 to 5 to be performed in the following order: 1. a step of applying a first composition to hair, wherein the first composition is acidic and comprises one or more selected from the group consisting of glyoxylic acid, glyoxylic acid hydrates, glyoxylates, and glyoxyl amides； 2. a step of leaving the hair having the first composition applied thereto to stand； 3. a step of heating the hair with a high temperature heating device； 4. a step of applying a second composition to the hair, wherein the second composition comprises an oxidizing agent, has a pH of 0.5 or more and. less than 8.0, and has a content of a dye component of less than 0.4% by mass； and 5. a step of leaving the hair having the second composition applied thereto to stand.本發明係一種毛髮處理方法，其包括按照以下之順序而實施之步驟1～5。 1.將含有選自乙醛酸、乙醛酸水合物、乙醛酸鹽及乙醛醯胺中之1種或2種以上且為酸性之第一組合物應用於毛髮之步驟 2.將應用有第一組合物之毛髮加以放置之步驟 3.利用高溫加熱器具將毛髮進行加熱之步驟 4.將含有氧化劑、pH值為0.5以上且未達8.0且染料成分之含量未達0.4質量%之第二組合物應用於毛髮之步驟 5.將應用有第二組合物之毛髮加以放置之步驟
