When image data obtained by scanning a document is to be registered in a document management system, a search index can be generated by layout analysis and object analysis. However, when application data generated by an application is to be registered, similar analysis processing cannot be done, and a search index cannot be generated. Hence, an instruction of application data to be registered in the document management system is received, and it is checked if that application data can be processed by the document management system. If it is determined that the application data cannot be processed by the document management system, the application data is converted into PDL data (S756), and the application data or data as a combination of the PDL data and application data is transmitted to the document management system.