PROBLEM TO BE SOLVED: To provide a second agent excellent in stability of hydrogen peroxide even under sunlight irradiation, the second agent being suitable for being filled into a dual-structured container which allows the remaining quantity to be confirmed visually, and also to provide an aerosol-type hair cosmetic composition and aerosol-type hair cosmetic article including the second agent in the composition thereof.SOLUTION: There is provided a second agent of an aerosol-type hair cosmetic composition which includes a first agent including an alkali agent and a second agent as an emulsion including hydrogen peroxide, the second agent being used by being filled in a dual-structured container. The container has a first inner vessel filled with the first agent and a second inner vessel filled with the second agent, the first and second inner vessels being provided separately and accommodated in the same outer vessel, a space between the outer vessel and each of the inner vessels being a propellant filling space filled with a propellant and the outer vessel and the second inner vessel being composed of a light transmissive material, to thereby allow visual confirmation of the inside of the second inner vessel from outside the outer vessel, and is provided with a mechanism for discharging the first agent and the second agent simultaneously. The average emulsified particle diameter of the second agent is 1 &mum or more.
