PURPOSE: To avoid the disturbance to the necessary positioning control when a rotary drum and a rotor are assembled and furthermore to maintain a state of an assured connection in a driving mode, by securing such a constitution where the free end of the 1st contact receives the displacement force toward the 2nd contact by the centrifugal force produced by the revolutions of the rotary drum and therefore a press-contact is secured between the 1st and 2nd contacts.

CONSTITUTION: For the 1st contact 12, an end is fixed at a supporting part 8 for attachment of a rotor 4 to be used as a fixed end with the other end used as a free end. The 2nd contact 14 which is connected to a magnetic head 5 is set at a place opposite to the free end of a rotary drum 6. No contact is secured with a large amount of pressure between both contacts 12 and 14 while the revolution of the drum 6 is stopped. Then a contact is secured between both contacts with a large amount of pressure when the drum 6 is revolved at a high speed since the free end 12b of the contact 12 receives the centrifugal force. Thus the transmission signal has an assured connection.