PURPOSE: To register and reproduce the information of a file name by an easy operation by displaying comprehensively all the image data in accordance with file names allocated first at every file to be selected.
CONSTITUTION: Prescribed pieces of image data are set as a file of one unit, and the prescribed pieces of image data at every prescribed number of files are read (S1). Then, the file names are registered by being allocated to all the image data in the file of one unit (S2). All the image data in accordance with the file names allocated first out of the data at every file are displayed comprehensively, and they are selected when retrieval is performed (S3). Such file allocation is performed prescribed number of times for every file when the file of one unit consists of prescribed pieces of image data.