1. An apparatus for checking value documents comprising: at least one sensor for capturing an electromagnetic radiation transmitted by a value document and generating corresponding first sensor signals which correspond to the electromagnetic radiation respectively transmitted in the region of the edge of the value document, and for capturing an electromagnetic radiation remitted by the value document and generating corresponding second sensor signals which correspond to the electromagnetic radiation respectively remitted in the region of the edge of the value document, and an evaluation device for checking whether the value document has a foreign object taking into account the first sensor signals and taking into account the second sensor signals; wherein the at least one sensor is configured for generating a transmission image, composed of first sensor signals, and a remission image composed of second sensor signals, and the evaluation device is configured for ascertaining on the basis of the first sensor signals one or more first edge points which correspond to the edge of the value document: ascertaining on the basis of the second sensor signals one or more second edge points which correspond to the edge of the value document; and checking whether the value document has a foreign object on a basis of any differences between an edge course of the value document ascertained from the transmission image and an edge course of the value document ascertained from the remission image.