An image forming device includes a control unit configured to control by sorting common setting information valid among a plurality of devices and specific setting information valid for a specific device, an internal storage device configured to store setting data that includes a pair of setting data of identification information indicating a type of setting item and setting values, an external storage device controller configured to control to input and output the setting data with a detachable external storage device, and a selective-write device configured to select and write the setting data read from the external storage device based on the predetermined criteria.