A double-aerosol device including: inner containers that separately store a plurality of types of hair treatment compositions used by mixing as hair dye, a decoloring agent, or dye remover; and an outer container in which a plurality of inner containers are stored; in which the hair treatment compositions are discharged to the outside by contracting the inner containers by a pressure of propellant, the outer container is configured such that at least a part of the inside of the outer container is visible so as to confirm remaining amounts of the hair treatment compositions, and the inner containers store the hair treatment compositions in pouches.