A water-soluble cationic polymer is applied to a sanitary product. The water-soluble cationic polymer has a structure including a main chain and a side chain bound to the main chain and has a molecular weight of 2000 or more. The water-soluble cationic polymer is a quaternary ammonium salt homopolymer or a quaternary ammonium salt copolymer. In the water-soluble cationic polymer, the main chain and the side chain are bound to each other at one point, and the side chain has a quaternary ammonium moiety. It is preferable that the quaternary ammonium salt homopolymer has a molecular weight of ten million or less. It is preferable that the quaternary ammonium salt copolymer is a copolymer of a polymerisable monomer having a quaternary ammonium moiety and a cationic polymerisable monomer, an anionic polymerisable monomer, or a nonionic polymerisable monomer, and has a molecular weight of ten million or less.
