PURPOSE: To obtain the stability for tape running by uniformizing the floating hight of the magnetic tape against a rotary cylinder and increasing the control force of a tape running system.

CONSTITUTION: In a specified central angle θ° of a fixed cylinder 2, the magnetic tape T is helically wound on the outside cylindrical surface and guided for running, then the rotary cylinder 1 is arranged coaxially with this fixed cylinder keeping a narrow gap 3 with the end surface thereof and rotated while winding the magnetic tape on the outside cylindrical surface common with the fixed cylinder, and a magnetic head 7 to record/reproduce for the magnetic tape is mounted on the outside cylindrical surface of the rotary cylinder. The rotary cylinder is formed to the tapered state so that the external size is gradually made smaller against the fixed cylinder, and plural V-shaped grooves are provided on the outside cylindrical surface of the rotary cylinder.