Abstract: A magnetic record/playback apparatus for continuously recording at least two tracks of data conforming to a digital recording format applied to a first magnetic tape having a first tape width onto one track formed on a second magnetic tape having a second tape width larger than the first tape width, and for reproducing the data from the second magnetic tape. This apparatus includes a fixed drum and a rotating drum adapted to be rotated relative to the fixed drum. The rotating drum has a record/playback head for recording and/or reproducing the data with respect to the second magnetic tape and an erase head for erasing the data recorded on the second magnetic tape. A plurality of grooves extending in a direction of rotation of the rotating drum are formed on the outer circumference of the rotating drum, and each of the grooves has a width of 0.21 mm±0.02 mm.