To obtain a device method, and storage medium for external character registration which make it possible to register and use obtained subordinate external character data even when the font of a subordinator is not existing in the system.

A CPU 101 executes an external character registration program which separates an external character data file obtained from an arbitrary location into an additional information part and an external character data part, stores the additional information part on a RAM 103 and the external character data part on an external storage device 109, confirms whether or not the font corresponding to the subordinate font name of the additional information part is registered on the system, and obtains and registers font data from a storage destination on the system according to font data size and also registers the external character data stored on the external storage device 109 as subordinate external characters of the font when the corresponding font is not registered.