PURPOSE: To facilitate the processing process wherein control is passed from an application program to a program stored on a memory card by automatically executing the program stored on the memory card when the completion of the mounting of the memory card is detected at the time of the execution of the application program.

CONSTITUTION: When the mounting of the card 5 is completed, an interruption process 9 is started. The state of the mounted card 5 is verified and application execution environment is saved. When there are plural executable programs 14 on the card 5, a menu display for execution program selection is made, input at a key part is accepted, and a program to be executed is selected. Here, process registration is performed. The control can be passed to the registered program without any problem since a process control table is initialized. After the execution of the program 14 on the card 5 ends, the control is returned to basic software 8 and the application execution environment is restored.