PURPOSE: To protect a secret of contents of a program by keying a program in a medium having a CPU, and limiting its use, copy, change, etc.

CONSTITUTION: A card 1 is set to a card reader 5, and a password is keyed in from a keyboard 6. An operating part 3 is started by a control device 8, checks the password in a memory 4, and when it coincides a program 2 is opened. The program 2 is started as one body with a program 10 in the control device 8, and can be brought to access to the memory 4 and a memory 9. Information which is not contained in the memory 4 is stored in the memory 9. The program 2 is a program for outputting a question about a key word in the memories 4, 9 onto a CRT7. When the question is keyed in from the keyboard 6 and all coincide, the information is sent to a computer 11 and processed. In this way, the key word is dispersed to the card 1 side and the control device 8 side.