PURPOSE: To improve contact characteristic of a tape and a head in a rotary cylinder head by providing a groove on the outer periphery of the cylinder based upon the position of a head mounting window as a reference.

CONSTITUTION: The head mounting window 4 is provided on the rotary cylinder 1. The groove 6 is provided on the place with about a half height of the window at the outer periphery of cylinder 1 in the position lower than the height of the window 4. This groove 6 is not formed in the completely closed annular state but disconnected in the neighborhood of the head mounting window corresponding to the backward side against the rotating direction of cylinder 1, thereby the difference in the floating amount of tape at the entrance side and exit side near the window is decreased, and the contact state for the tape and head is improved.