To provide a noncontact card device including the noncontact card which gains needed power by electromagnetic induction waves transmitted from a reader and transmits the desired information to the reader.

This noncontact card device consists of a reader and a noncontact card, the reader transmits electromagnetic induction waves having a 1st frequency to the non-contact card and generates electromotive force, the noncontact card transmits the electromagnetic induction waves having a 2nd frequency obtained by dividing the 1st frequency to the reader, and the reader confirms existence of the noncontact card and its operation state. Subsequently, the reader transmits the electromagnetic induction waves having the 1st frequency obtained by modulating the information, making the noncontact card function to the noncontact card, gives a demodulated signal together with a timing clock to a nonvolatile storage element of the noncontact card and reads or stores the desired information, and the electromagnetic induction waves having the 2nd frequency obtained by modulating the information from the nonvolatile storage element are transmitted to the reader.