PURPOSE: To eliminate the need for an operation of setting the switching time of a power source by automatically controlling the switching of the power source according to the past device using state.

CONSTITUTION: In this image forming device is provided with a means 2 which is executed regardless of the switching state of the power source of the image forming device, produces information on a device using state, in each time zone at intervals of a prescribed time, and stores it in a storage means 2, and a means 4 which is executed regardless of the switching state of the power source of the image forming device, and outputs a command for switching the power source of the image forming device, based on the information on the device using state of the applicable time zone, stored in the storage means 2 at the relevant time zones.