Method for manufacturing noncontact communication medium and noncontact communication medium

A method for manufacturing a noncontact communication medium including a processing circuit that is mounted on a substrate on which an antenna coil configured to induce power with application of a magnetic field from an outside is formed, and has an internal capacitor, and an external capacitor that is externally attached to the processing circuit and composes a resonance circuit configured to resonate at a predetermined resonance frequency with application of the magnetic field, along with the internal capacitor and the antenna coil, the processing circuit operating using power generated by the resonance circuit, the method comprising:

• measuring a temporary resonance frequency in a state in which the external capacitor is not connected to the processing circuit and in a state in which the processing circuit is connected to the antenna coil;
• deciding capacitance of the external capacitor based on a degree of difference between a reference resonance frequency in a case where the noncontact communication medium performs communication with the outside through the magnetic field and the temporary resonance frequency;
• and
• forming the resonance circuit by mounting the external capacitor, having the decided capacitance, on a surface of the substrate by a surface mounting method, and connecting the external capacitor to the internal capacitor.