To provide a crosslinked body of a carboxymethyl cellulose obtained without using a crosslinking agent, an activator, a polyvalent metal ion, a reaction by-product or the like, and utilizable as a concrete material for a medical device used in embedding application; and to provide a method for producing the crosslinked body.

The crosslinked body of the carboxymethyl cellulose is obtained by freezing an acidic solution containing the carboxymethyl cellulose having 1,000-12,000 mPa_s viscosity (1% solution 25°C), and having pH 0.2-3.5, and thawing the frozen product.