PURPOSE: To reduce the height of a rotary head drum and to make the weight of the drum light by fitting a rotary side core directly to an upper end face of a rotary disk projected to the upper side of the rotary drum.

CONSTITUTION: A stationary drum 21, a rotary disk 31 supported freely rotatable by the stationary drum 21 at the upper side of the stationary drum 21, a rotary drum 35 fixed to the upper part of the rotary disk 31 and supporting the rotary heads 37, 38 and a rotary transformer 42 arranged at the upper part of the rotary drum 35 and having a stationary side core 48 and a rotary side core 43 are provided. The rotary disk 31 is projected to the upper side of the rotary drum 35 while being penetrated through the rotary drum 35 and the rotary side core 43 is fitted to the upper end face of the rotary disk 31 projected to the upper side of the rotary drum 35. Thus, the accuracy of deflection of the face of the rotary transformer 42 is improved and the height of the rotary head drum is reduced and the weight of the drum is made light.