PURPOSE: To provide the computer system which can improve the operability of an operator by varying the set time of an automatic power-OFF process according to whether or not the operator is present.

CONSTITUTION: A CPU 1 performs the automatic power-OFF process unless the operator 12 performs key input operation on a keyboard 2 for a specific set time. A sensor 11 detects the operator 12 being present nearby the system. When the sensor 11 detects the operator 12, the set time of the automatic power- OFF process is made longer. Consequently, when the operator 12 is present, the automatic power-OFF process is performed the relatively long time later.