To provide a cosmetic base efficiently protecting the human skin from skin cancer caused by ultraviolet rays, and being friendly to a human being and to the environment.

The cosmetic base has fiber masses each having a light-scattering honeycomb structure in which the size of each hole is 1-2 m and the diameter of each whole mass is 40-400 m, each fiber has a right-handed helix twist structure and fineness of 80-100 nm, and the fiber is composed of -1,4-glucan formed by the fermentation of acetobacterium and contains -1,3 glucan derived from a sporophyll of sea mustard and a lipid in the hole part of the honeycomb structure. The cosmetic base is characterized in that it has ultraviolet ray-scattering effect and moisturizing and sustained-release effect based on chemical equilibrium.