PURPOSE: To accurately control an IC card by setting he distance between a clock oscillator, to which a clock signal having a high frequency flows, and a portable recording medium to a short value and allowing a binary logical signal for control to flow to a cable between an external control part and read/write device.

CONSTITUTION: A clock oscillator 33 which supplies an operating clock to the portable recording medium through a contact part 22 and a logic circuit which is controlled by the binary logical signal from the external control part and selectively supplies the clock of the clock oscillator 33 to the portable recording medium are incorporated. In case of data transmission and reception between the external control part and the IC card through a read/write device 20, the clock oscillator 33 is arranged in the read/write device 20, and the distance between the clock oscillator 33 to which the high frequency signal flows and the IC card is set to a very short value. The binary logical signal which controls the logic circuit or the like with the change of the signal level flows to a cable 18 between the external control part and the read/write device 20. Thus, crosstalk and reflection do not occur on signal lines and the IC card is accurately controlled.