Multiple user boxes are created beforehand in the hard disk drive of the MFP. The user specifies his own user box and saves image data therein. If the user extracts the image data from his user box and moves it to a folder on his own personal computer, the MFP 1 detects this action. When this user box is specified during a subsequent reading of image data, the storage destination for the image data is automatically deemed to be the folder on the personal computer to which the image data was previously moved.