A cooking appliance includes a housing that defines a cavity therein, a door connected to the housing and configured to open and close the cavity, a microwave (MW) heating module configured to emit microwaves into the cavity, and an induction heating (IH) module configured to emit a magnetic field towards the cavity. The IH module includes a working coil that is configured to generate the magnetic field and a thin film that is disposed between the cavity and the working coil.