An apparatus for processing value documents, in particular banknotes, comprises more processing zones respectively having at least one cover for covering an internal space of the processing zone in question. An interior lighting means is provided and at least one region of the cover or adjacent to the cover is semitransparent. The internal space can thus be viewed through the semitransparent region only when the interior lighting means is switched on. Upon detecting an error in the bank note processing, the interior lighting means of the processing zone in question lights up automatically, thus guiding the operator directly to the location of the problem.