PURPOSE: To raise the insulation reliability of an autotransformer and make it compact, by picking out a lead for an end of shunt winding for connecting the end of the shunt winding and both the ends of a series winding to an identical terminal, through the gap between divided parts of an electrostatic shield at an end of the series winding.

CONSTITUTION: The electrostatic shield 17 for the series winding 4 outside the shunt winding 3 is divided between spacers 18 uniformly placed along the circumference of the series winding 4. The lead 8 for the upper end of the shunt winding 3 is picked out through the gap between the divided parts 17a of the shield 17 and connected to a secondary terminal. Because the lead 8 is not picked out upward from the tops of the electrostatic shields 16, 17, no electric field is concentrated around the lead 8 and the divided parts 17A. Since the lead 8, the electrostatic shield 17 and the end of the series winding 4 have almost the same potential, no problems arise as to the electric insulation. The sections 4A of the series windings 4 are tightened with clamping members 13 without hindrance. As a result, the insulation reliability is raised and the autotransfomer is made compact.