PURPOSE: To prevent entering of a magnetic tape into a gap at the time of tape running and the pccirrence of a tape beating phenomenon by housing an induction coil consisting of a head and an adhesive material attaching the magnetic had to a head base inside a rotary drum, and eliminating a recessed groove part penetrating the outer peripheral surface of the rotary drum.

CONSTITUTION: At least a step Tv of thickness CW or above of a core 8 loaded on the drum 1 is provided between the attaching surface (d) of the head base 10 of the rotary drum 1 and a lower end surface (e) of the outer peripheral surface in the direction where the lower end surface (e) of the outer peripheral surface of the drum 1 becomes higher in the direction of drum height. Thus, when a head mechanism 6 is attached to the drum 1, the mechanism 65 is attachable so that the coil 7 and the adhesive material 11 are not in contact with the drum 1. Further, the height of the upper end surface (f) of the outer peripheral surface of the drum 2 is made to be a height being not in contact with head 9 stuck on the drum 1, and the gap (t) between both drums is held to a nearly equal size to the conventional one in the thickness CW of the core 7. Thus, no tape enters into the gap, and the tape beating phenomenon is eliminated.