[Problem] The objective of the present invention is, in a kit that is for preparing a carbon-dioxide-containing composition containing an oxygen-containing gel composition and a carbonate-containing gel composition, to provide a formulation technology enabling uniform and easy mixing, uniform generation of carbon dioxide, and the prevention of dripping down when applied to skin. [Solution] In the kit for preparing a carbon-dioxide-containing composition, by means of selecting the combination of a gel composition (1) containing a hydrophobically modified alkyl cellulose, an acid, and water, and a gel composition (II) containing sodium alginate, a carbonate, and water, it is possible to obtain uniform mixing by means of a two-agent mixing device, uniform generation of carbon dioxide, and the prevention of dripping down when applied to skin.
