PROBLEM TO BE SOLVED: To provide a hair dye composition which can easily provide a foamy hair dye, and can easily dye or bleach/decolor the hair in a short time without uneven coloring.SOLUTION: A hair dye composition to be used with an open-bottomed container and a foaming net of a mesh fiber material comprises a plurality of agents, any of which contains an alkali agent, an oxidant, and a surfactant, and at least one of which is a liquid agent and is applied to the hair in a foamed state by making the plurality of agents pass through the foaming net of the mesh fiber material having stitch number (2) and (3) in an open-bottomed container one or more times with manual operation to mix.
