Image data in a specific data format is stored in an external storage device, whereas application software for display, editing, and printing of the image data in the specific data format is not stored in the external storage device but transmitted to an e-mail address of a user or to an IP address of a user's computer. This provides a digital multifunction printer which is capable of storing image data in a removable external storage device and which can store image data in the external storage device in such a manner that the image data is stored with a data format specific to the digital multifunction printer while the image data can be processed by other device without dropping security for the stored image data.