A radio IC device includes a radio IC element that includes an antenna terminal connected to an antenna element, and a ground terminal connected to a ground conductor provided integrally with the antenna element, and a circuit element that includes an impedance matching circuit connected to the antenna terminal of the radio IC element. The circuit element includes a first inductance element that defines the impedance matching circuit, and a second inductance element that is connected, as a high-frequency cutoff circuit for the radio IC element, to the ground terminal.