An X-ray reading device, for reading out X-ray information stored in a phosphor plate, includes an insertion device into which a cassette in which the phosphor plate is located, can be inserted, and an oblong insertion opening through which the phosphor plate located within the inserted cassette can be conveyed into an inside cavity of the X-ray reading device. In order to guarantee a reliable light seal with a simple closure mechanism which can accommodate different position tolerances and cassette formats, at least one closure mechanism is provided which can be moved in a longitudinal direction of the insertion opening to close at least one second section of the insertion opening.