A new filename after change is generated based on rules set using a filename setting menu (301), extension format selection menu (302), basic setting menu (303), and format setting menu (304), and is displayed on a new filename list display window (306). In this case, if the new filename is unusable, it is displayed in distinction from other filenames, thus informing the user of it. A file management apparatus can detect in advance whether or not an error may occur upon changing the filename and can notify the user of such error.