Abstract: A rotary transformer assembly of a rotary head drum device, comprising a plurality of concentric circular shielding walls for isolating adjacent pairs of channels from each other so as to prevent a leakage of electromotive force between the pairs of channels and a plurality of concentric circular slots for receiving the ends of the shielding walls so as to isolate the adjacent pairs of channels from each other in combination with the shielding walls. The shielding walls are provided at one of the transformer rotor and the transformer stator as protruding at the outer side of the outermost channel, at the inner side of the innermost channel and at a position between each adjacent pairs of channels. The slots are provided at portions, corresponding to the shielding walls, of the other of the transformer rotor and the transformer stator.