An image forming device is disclosed which includes an open/close switch for detecting the opening and closing of a manual feed tray, and a power control unit for turning on specific power when the open/close switch detects that the manual feed tray has been opened. When the manual feed tray is opened, the use is assumed to be about to use the image forming device, and thus energy conservation becomes possible because the specific power is turned on only at this time. Moreover, the drive power for the bypass unit and the main power of the image forming device is defined to be this specific power.