Provided is a hair dye composition to be used as a mixture of a first part containing an alkali agent and a second part containing an oxidizing agent, wherein the composition comprises (a) a triazacyclononane compound (1) or salt thereof, (b) 0.1 to 12 wt. %, in terms of hydrogen peroxide, of an oxidizing agent, and (c) 0.05 to 10 wt. % of an alkali agent, and the mixture has a pH of from 7.5 to 12.
(R1 to R4: H or C1-6 alkyl which may be substituted by OH, R5 to R7: H, (substituted) C1-6 alkyl, (substituted) aralkyl, (substituted) heteroarylalkyl, (substituted) aryl, (substituted) heteroaryl, (substituted) C1-6 acyl, or a group (2) (in which R8 to R12 represents H, C1-6 alkyl, aralkyl or aryl and n stands for 2 to 30).
The hair dye composition of the present invention has excellent hair bleaching power, can dye the hair into a bright favorable color tone, and moreover has less hair damage and less scalp irritation.