PURPOSE: To prevent the malfunction of the damage of an IC card by providing a small hole for detecting a position in the IC card.

CONSTITUTION: The IC card 1 has an electrode terminal 3 at one side and small holes 2 for detecting a position at both corners at the other side. When the IC card 1 is inserted into a connector part 16, a signal is fed to a control circuit 15 from a computer terminal equipment 17, thereby, converged light is projected to the small holes 2 respectively of the IC card 6 by a two lens having light emitting diode 12 through a light emitting diode driving circuit 11. The light passing through the two small holes 2 is received by respective phototransistors 13. The signal of the quantity of the received light from the two light receiving phototransistors 13 is transferred in a light receiving signal transfer circuit 14 and the control circuit 15 decides whether the inserted state of the IC card 1 to the connector part 16 is normal or abnormal according to the transfer signal.