Carboxymethyl cellulose (CMC) is one of the most important cellulose derivatives and used in the fields of food, pharmaceuticals, cosmetics, and paint. Fibrous CMC is used an antiadhesive material to prevent postoperative wound adhesions. The degree of substitution and distribution of the substituent (i.e., the carboxymethyl group) are the most important parameters for the function of CMC. Thus, CMC used for antiadhesive material must be carefully evaluated, because the CMC product is retained in patients' bodies over the long term. Although identification tests of CMC are defined in the Japanese Pharmacopoeia, it is difficult to evaluate its structure using those tests. In the present study, we propose improved methods for evaluating CMC products by analyzing monosaccharides after hydrolysis.