PURPOSE: To prevent the excess battery consumption by selectively performing the electric power source disconnection processing or resume processing according to the length of the input operation time of a power source switch even in a resume processing selection mode setting state.

CONSTITUTION: The personal computer consists of an input device 30 for data input, a RAM 20 storing the inputted data, a ROM 10 storing a program for controlling this personal computer, a central processing unit 40 performing control according to the program instruction stored in the ROM 10, a power source switch 60 turning on and off the power source of the personal computer, and an output device 50 outputting the processing result. When the system is set to perform the resume processing in turning off the power source switch 60, the power source disconnection processing or the resume processing is selectively performed according to the operation method of the power source switch 60 in operation.