The present invention is a hair treatment method including the following steps. Step (i): a step for applying to the hair a first composition including a carboxylic acid having an inorganic value of 250-450 and an organic value of 50-250 or a salt of said carboxylic acid as component (A)； step (ii): a step for allowing the hair to which the first composition has been applied to stand for from 15 seconds to 60 minutes at 15-100 DEG C； step (iii): a step for applying to the hair a second composition including an aromatic sulfonic acid having a molecular weight of 300 or lower or a salt thereof as component (B) after step (ii).本發明之毛髮處理方法包含以下步驟： 步驟(i)：對毛髮應用含有無機性值250～450且有機性值50～250之羧酸、或該羧酸之鹽作為成分(A)之第一組合物之步驟， 步驟(ii)：將已應用第一組合物之毛髮於15～100℃下放置15秒～60分鐘之步驟， 步驟(iii)：於步驟(ii)後，對毛髮應用含有分子量為300以下之芳香族磺酸或其鹽作為成分(B)之第二組合物之步驟。
