A process for producing a water-insoluble shaped material, including a step of treating a raw material shaped material containing a water-soluble salt of a polyanionic polysaccharide with a treatment liquid containing an acid anhydride to insolubilize the raw material shaped material in water, and the process makes it possible to simply produce a water-insoluble shaped material in which intrinsic characteristics of the polyanionic polysaccharide being a raw material are retained, which has a high safety in that a chemical crosslinking agent is not required, and which is useful as a medical material, a food material, a cosmetic material, and the like.
