A radio frequency IC device achieves impedance matching between a radio IC chip and a radiation plate in a wide frequency band, and achieves desired radiation characteristics over a wide range of frequencies. A radio frequency IC device and a radio communication system allow both long-distance and short-distance communication and, in particular, allow short-distance communication using a small amount of energy. The radio frequency IC device includes an electromagnetic coupling module including a radio IC chip and a feed circuit board, and a radiation plate. An annular electrode is arranged to be coupled to both a feed circuit of the electromagnetic coupling module and the radiation plate. The radiation plate defines an electric-field radiation plate for long-distance communication, while the annular electrode defines a magnetic-field radiation plate for short-distance communication. The feed circuit board may be removed, so that the radio IC chip is coupled to the annular electrode directly or with an interposer disposed therebetween.