HAIR DYE COMPOSITION

Disclosed is a hair dye composition which is used by mixing a first agent containing an alkali agent with a second agent containing an oxidizing agent immediately before use. This hair dye composition is characterized in that at least one of the first agent and the second agent contains a diazacycloheptane represented by the general formula (1) below or a salt thereof, and the pH after mixing is within the range 7.5-12. (1) (In the formula, Z represents a hydroxy group, a primary amino group, or a C1-4 acyloxy group; R1 and R2 independently represents H or an optionally branched C1-4 alkyl group; and R3 represents H, an optionally branched C1-6 alkyl group or C1-6 alkoxy group, or an aralkyl group or aryl group having 12 or less carbon atoms in total which may be substituted with one or more C1-4 alkyl groups or alkoxy groups.)