Compositions for preparing external carbon dioxide agents comprising a granular material containing a water-soluble acid(s), a thickener(s) and a water-soluble dispersant(s) as the essential components wherein the thickener(s) is (are) mixed with the water-soluble acid(s) and the water-soluble dispersant(s), and a viscous material, which consists of a carbonate(s), water and a thickener(s) as essential components; to be mixed with the said granular material at use, by which an external carbon dioxide agent can be prepared easily in a short period of time. The prepared external carbon dioxide agent, containing much carbon dioxide evenly all over, has sufficient viscosity and can form a coating film on the surface in contact with air, therefore the diffusion of carbon dioxide is suppressed, the applied agent does not droop and its thickness is not reduced when applied to skin or mucosa; and the agent shows potent and quick cosmetic and medical effects.