PURPOSE: To reduce the number of power sources and to prevent the destruction of write data by interpolating the other power source by means of one power source in an IC card which requires more than two power circuits.

CONSTITUTION: In the power circuits of the card, the voltages of a Vcc terminal 12 and a Vpp terminal 13 impressed on a semiconductor memory 2a become equal to (3) by the voltage values of input voltages (3) and (4) when (3)≥(4), and the voltage of the terminal 12 becomes equal to (3), and the voltage of the terminal 13 to (4) when (3)<(4). Thus, diodes 10 and 11 transmit the voltage inputs of Vcc and Vpp from an IC card read/write device to Vcc and Vpp of the semiconductor memory without changing the voltages in write/elimination operations. In a read operation on the other hand, the diodes 10 and 11 make the Vpp voltage and the Vcc voltage to the same potential. Thus, the voltage difference of Vcc and Vpp, both of which are impressed on the memory 2a is eliminated and one power is eliminated.