A non-contact communication medium according to one disclosed embodiment includes a memory unit, a power generation unit, a power monitoring unit, and a capacitance control unit. The power generation unit includes a resonant circuit and a rectification circuit, and generates electric power to be supplied to the memory unit. The resonant circuit includes an antenna coil and resonant capacitance unit having a variable capacitance value, and the rectification circuit rectifies a resonant output of the resonant circuit. The power monitoring unit includes a current adjustment element, a reference voltage generation source, and an operational amplifier. The operational amplifier controls the current adjustment element such that an output voltage of the rectification circuit is equal to a reference voltage from the reference voltage generation source. The capacitance control unit is configured to control the resonant capacitance unit on the basis of an output of the operational amplifier.