To provide an image processor, its control method and a storage medium capable of storing a control program and a resource corresponding to the control program with accurate correspondence and enabling a user to simply switch and display a required display language.

Starting information is acquired at first (step S1). When the starting information includes information concerned with a display language, whether a resource file corresponding to the language exists or not is checked, and when the resource file exists, management information for the resource file is read out (steps S2→S3). Then the version and data size of the resource file are checked, and when the version of the resource file coincides with that of a control program and the capacity of the resource file is less than prescribed capacity, resource data included in the resource file are read out (steps S4→S5→S6).