PURPOSE: To execute a control means even if the capacity of a non-volatile memory and that of a volatile memory are not sufficient for the capacity of the control means (program).

CONSTITUTION: Data is stored in the non-volatile memory 7 in the state of a compression control means (compressed program) obtained by compressing the control means (program). The volatile memory 8 is constituted to store execution control means (execution possible programs) for respective areas. A management means 1 reads the compression control means from the non- volatile memory 7 by a read means 2, expands the compression control means to the execution control means by an expansion means 3 and writes it into the necessary area of the volatile memory 8 by a write means 4. The write means 4 is managed so that the area which is written the most formerly is set to be a write area when there is no idle area in the volatile memory 8.