PURPOSE: To prevent the insertion of a recording media with different specifications and foreign matters and an iron plate, etc., and to prevent the trouble and the destruction of a recording medium reading device by discriminating, before the insertion, that the medium is the portable recording media applicable to the recording media reading device.

CONSTITUTION: When an IC card 1 is removed to the external part, the electric power source is supplied from a solar battery 5 to an oscillating circuit 11 by the external light, the electric signal of a special frequency f1 is oscillated, the oscillating signal is supplied to a light emitting element 3 and outputted from a light emitting element 3 to the external part as an identifying signal S1. When the IC card 1 is inserted into a card inserting port 21, a light receiving element 33 supervises whether or not the identifying signal S1 is received, and when the identifying signal S1 is received, the identifying signal S1 is converted to the electric signal and supplied to a detecting circuit 35. A detecting circuit 35 decides whether the identifying signal S1 is the signal applicable the card reading device or not. When the identifying signal S1 is the signal applicable to the reading device, the inserted IC card is the right IC card, and therefore, a shutter 23 is closed.