An integrated circuit, a non-contact IC card, a reader/writer, a wireless communications method, and a computer program are provided to improve communication. The integrated circuit configured to execute wireless communication by means of magnetic field. The integrated circuit has a resonance circuit having resonance frequencies of a plurality of levels, a confirmation block configured to confirm whether a predetermined condition is satisfied, and a switching block configured to change the resonance frequencies if the predetermined condition is found satisfied as a result of the confirmation.