In an IC card 30 is sealed an IC chip 70 provided with an exposure
sensor 84. When exposure sensor 84 detects that IC card 30
has been opened, exposure sensor 84 outputs an exposure detection signal
to a CPU 76. In response to the exposure detection signal, CPU 76
provides a predetermined operation, such as erasure of data in a non-volatile memory
78. As such, the data in non-volatile memory 78 cannot be obtained
if IC card 30 is improperly opened to check the data in non-volatile memory
78. Thus the IC card can obtain an enhanced data security.