PURPOSE: To prevent diversion of a data, a program or a circuit, and to maintain secrecy, by limiting a time when a memory can be diverted, recording the diversion of a memory, recording a movement of a circuit substrate, detecting the reset of metal fittings for setting a memory circuit substrate, etc.

CONSTITUTION: A timer 2 which is able to freely set a time when a data in a memory can be read out, written or erased is provided in front of a memory read-out and write erasing device 5 of a memory 1, and a time when the memory can be utilized is set by this timer, and it is made impossible to utilize it except said time. The memory 1 is formed in one unit together with an electric power source 20, and can be attached and detached freely. An indicator 6 for displaying the timer 2 is provided on an input/output device 10, and read-out write and erase of the memory are executed by an operation control device 9. In addition, diversion of the memory is recorded by an auxiliary memory, diversion of the memory is controlled, and secrecy is maintained.