PURPOSE: To compensate external factors by guiding a document or a partial document to the scanning position in front of a television camera type photoelectric scanner assigned to each kind of documents or partial documents by a conveyor device.

CONSTITUTION: A document or a partial document is guided from a group 4 of documents or a part 5 of partial documents to the scanning position in front of a television camera type photoelectric scanner 6 or 7 assigned to the group of documents or partial documents by conveyor devices 1 and 2. The text part of the document or the partial document is scanned, and the scanning result is converted from an analog signal to a digital signal and is constituted of a series of digital signals, and the series of signals are compared with one another by a comparator 8. Thus, external factors such as the difference in light intensity, dust, and the angular error are compansated.