A zwitterionic resin is manufactured by a manufacturing method which includes the following steps. A first thermal process is performed on a first crosslinking agent and a choline having hydroxyl group or amino group to form a first mixture, in which the first crosslinking agent includes an isocyanate group. A second thermal process is performed on the first mixture, a second crosslinking agent, a chain extender, and an amino acid to form the zwitterionic resin, in which the chain extender includes a polyol.