PURPOSE: To prevent an IC card from being robbed or lost by providing the IC card itself with a function for outputting an oscillating wave and providing an article that a card holder puts on, e.g. a wrist watch with an input function for the oscillating wave.

CONSTITUTION: An ultrasonic wave from the wrist watch 31 is outputted to the space through a transmitting part 32 and this ultrasonic wave is supplied to the receiving part 13 of the IC card 11 and converted by a power converting circuit 23 into electric power energy, which is supplied to a CPU 21. Then, an ultrasonic wave obtained by the internal oscillator of a CPU 21 is outputted from a transmitting part 14 and inputted to the receiving part 39 on the side of the wrist watch. Then, when the oscillating wave energy of the ultrasonic wave inputted to the receiving part 39 drops below a specific level, a level decision part 40 outputs an alarm signal to a buzzer 38. Therefore, the card holder knows that the IC card has left the holder from the warning tone of the buzzer.