A magnetic recording/reproducing apparatus with a drum positioning mechanism is provided. The drum positioning mechanism performs track correction to rotate a tape guide drum about a given axis of rotation according to a travel speed of a magnetic tape to orient a head path of magnetic heads at a given angle relative to a lead member which guides movement of a lower edge of the magnetic tape wrapped about the tape guide drum so that the head path coincides with tracks recorded on the magnetic tape correctly. The drum positioning mechanism also performs lead correction to rotate the lead member through a given angle relative to a drum base to eliminate a shift of the lower edge of the magnetic tape from the lead caused by the track correction so that the lower edge of the magnetic tape follows the lead completely. The magnetic recording/reproducing apparatus may also be employed in a recording mode. In the recording mode, the head path is oriented by the track correction at a preselected angle to the lower edge of the magnetic tape.