A device to be equipped on a magnetic recording and reproducing system can meet a plurality of recording formats and carry out stabilized recording/reproducing without depending on the running direction (A,B) of the magnetic tape (51). There are combined either of at least two thin film magnetic heads (81a,81b) for recording each having on a substrate a recording transducer for recording information on a magnetic tape or two thin film magnetic heads for reproducing each (71a,71b) having a reproducing transducer for reading out information recorded on a magnetic tape or two thin magnetic heads (50a,50b) for recording and reproducing in which the recording converter and the reproducing transducer exist in mixture. According to the running direction of the magnetic tape, only the thin film magnetic head (50a) which is situated at the downstream side in the running direction (A) of the magnetic tape is activated to be always in an operating condition.