Abstract: A method for treating hair, comprising steps 1 and 2 below: (step 1) applying a hair dye composition to hair to dye the hair; and (step 2) applying a hair treatment agent to the hair subjected to hair dyeing in the step 1, the hair treatment agent comprising the following components (A), (B) and (C) and having a pH of 4 or less or 8 or more: (A) an epoxy-aminosilane copolymer which is a reaction product of the following compounds (a) to (d): (a) a polysiloxane having at least two oxiranyl groups or oxetanyl groups; (b) a polyether having at least two oxiranyl groups or oxetanyl groups; (c) an aminopropyltrialkoxysilane; and (d) a specific primary and secondary amines; (B) water; and (C) a pH adjuster.

Abstract: An oil-in-water type one-part hair dye composition containing components (A), (B), (C) and (D); (A) a direct dye; (B) a hydrocarbon oil; (C) a polyoxyalkylene-modified dimethylpolysiloxane with an HLB of 7 or higher; and (D) an aromatic alcohol; wherein the content ratio by mass of the component (B) to the component (C), (B)/(C) is 0.05 to 10.

Abstract: An oil-in-water type one-part hair dye composition containing components (A), (B), (C) and (D); (A) a direct dye; (B) a hydrocarbon oil; (C) a polyoxyalkylene-modified dimethylpolysiloxane with an HLB of 7 or higher; and (D) an aromatic alcohol; wherein the content ratio by mass of the component (B) to the component (C), (B)/(C) is 0.05 to 10.

Abstract: A hair cosmetic composition containing (A) a cationic surfactant; (B) one or more organic solvents selected from among an N-alkylpyrrolidone, a lower alkylene carbonate, and an aromatic alcohol; (C) a lower alcohol or a lower polyol; and (D) an alkaline ingredient. The composition efficiently removes an acid hair-dye composition from the hair without causing any damage to the hair.