PURPOSE: To prevent a power supply control device from any influence even if the constitution of a computer system is changed by forming switches individually corresponding to device names in all devices of the computer system.

CONSTITUTION: When a POWER-ON command is inputted by using the device name of a device 11 used by the computer system 1, a power supply control program loaded to a memory 42 decodes the command. Then, the power supply control program indexes a corresponding table for the device names and device code values to convert the device name into its individual device code. Power ON is commanded on the basis of the device code value through a serial power supply interface 5. Since a switch value has been previously set up in the switch 11a of the device 11, a power supply for the device 11 can be turned on. In case of the disconnection of the power supply, the power supply for the device having the device name specified by a POWER-OFF command is disconnected by the similar operation to the power ON operation.