There is provided a small radio frequency IC device capable of easily achieving impedance matching without a dedicated antenna and an electronic apparatus. The radio frequency IC device includes a radio frequency IC chip (5) for processing a transmission/received signal, a printed circuit board (20) on which the radio frequency IC chip (5) is mounted, an electrode (21) formed at the circuit board (20), and a loop electrode (22) that is formed at the circuit board (20) so that the loop electrode (22) is electrically connected to the radio frequency IC chip (5) and is coupled to the electrode (21) by electromagnetic coupling. The electrode (21) is coupled to the radio frequency IC chip (5) via the loop electrode (22) so as to transmit or receive a high-frequency signal. A power supply circuit board including a resonance circuit and/or a matching circuit may be disposed between the radio frequency IC chip (5) and the loop electrode (22).