Method and device for printing on a medium and for detecting and reading information recorded on the medium

Disclosed is a device for processing media to check the validity of checks and other negotiable instruments and print as necessary on said media. The device comprises in sequence along a transport path (9) from an insertion opening (6) a transportation mechanism (3), a printing mechanism (4) and a reading mechanism (5). When the medium (8) is transported by the transportation mechanism (3) along the transport path (9) to a predetermined position, the check is positioned between a presser roller (51) and a sensor (52) of the reading mechanism (5). The presser roller (51) then presses the check (8) against the sensor (52) while the transportation mechanism (3) pulls the check and information recorded on the check is read. This operation straightens wrinkles and removes slack from check (8) to reduce reading errors. Based on the read information, a printing process is then executed by the printing mechanism (4) and the check is ejected from the insertion opening (6). Task efficiency is therefore good, and the occupied space can be minimized.