PURPOSE: To provide the display method for icon so as to provide memory capacity with a folder icon displaying the group of data as an icon.

CONSTITUTION: In the case of performing the icon display of document data stored in a memory 25, a folder collecting several data is prepared, and it can be displayed as the icon. In the case of display, first of all, data are expressed in relation with icons. When the icon shows the document data, that icon is displayed as it is but in the case of the folder icon, the storage capacity required for the document data contained in the folder is summed up and the calculated storage capacity is displayed together with the folder icon. On the other hand, not the capacity but the number of document data contained in the folder can be displayed as well.