Disclosed herein is a rotary head drum unit including a cylindrical drum surface and a magnetic head for recording/reproducing a signal to/from a magnetic tape running along the drum surface. The magnetic head has a tape sliding surface adapted to come into sliding contact with the magnetic tape. The tape sliding surface of the magnetic head is positioned at a level lower than the height of the magnetic tape flying above the drum surface. The magnetic tape is brought into contact with the tape sliding surface by negative pressure. With this configuration, an increase in contact pressure of the magnetic tape sliding on the tape sliding surface of the magnetic head can be prevented and the contact pressure can be uniformed to thereby prevent a reduction and variations in magnetic recording or reproduction output.