PURPOSE: To efficiently conduct storage work of documents by making an image display based upon display settings when an error in reading retrieval information is generated.

CONSTITUTION: If a bar code is not decoded normally owing to a stain of the document, information showing a failure in decoding is sent from a bar code reader 300 to a CPU 10. The CPU 10 once receiving it does not feed a next document stack on an original platen, so the storing operation is stopped temporarily at the point of time. At the same time, a display showing the failure in reading the bar code is made on a display 32. In this state, the CPU 10 indicates the start of a read scan on the bar code to a handy bar code reader 310 as a 2nd retrieval information read means. Therefore, an operator takes the original out of a paper discharge part and applies the handy bar code reader 310 to read the bar code.