PURPOSE: To prevent the useless input of characters in a document name by comparing words included in a sorting name with that included in a document name at the time of setting up the document name, and when the same word is included, generating an alarm.

CONSTITUTION: When the processing of a document image processor is specified by an input device 5, a main control part 4 retrieves a storage medium 8 with 4 retrieving means 7 when the specification indicates the setting of a name, and when there are already set sorting names, displays the sorting names on a display device 3 and the device 5 selects one of the sorting names. When there is no required sorting name, a sorting name is inputted from the device 5 and temporarily stored in a memory 9. The sorting name is compared with the one retrieved by the means 7 to judge the existence of the same word, and when the same word exists, the contents are displayed on the device 3 as an alarm. Consequently, the useless input of characters in a document name can be prevented.