An IC card is set to an RF mode by default when drive electric power starts being applied to the IC card. When both a clock signal and a reset signal are applied to respective connection terminals, the IC card switches to a terminal mode. The clock signal and the reset signal that are applied to the respective connection terminals can be detected without the need for an analog circuit such as a comparator. The IC card can be switched between the terminal mode in which only input signals applied to the connection terminals are effective and the RF mode in which only an input signal applied to a radio antenna is reliably effective, with only a digital circuit.