PROBLEM TO BE SOLVED: To provide a kit for obtaining a foamable skin external preparation which can be used by application to the skin after developing foam due to carbon dioxide generation by appropriately mixing a first agent and a second agent in use, is easy to be uniformly mixed, generates carbon dioxide without unevenness, and achieves consistent quality regardless of troublesome measuring by a user and the quality of water used.SOLUTION: In a kit, a first agent is a composition containing an acidic substance, a carbon dioxide generating substance reacting with the acidic substance to generate carbon dioxide, and a thickener, and a second agent is a composition containing water and/or a humectant. The first agent is a solid composition, and the acidic substance and/or the carbon dioxide generating substance have a coat layer and co-exist so that they are not in contact with each other.
