PURPOSE: To prevent a seal portion from solution leakage cause by wear, damage, etc. by punching a copper system or aluminum system plate blank to constitute a conductive portion of a rotor laminated with planer plates of electromagnetic iron core from both surfaces.

CONSTITUTION: A rotor conductor 15 using copper or aluminum system blank is punched from a plate material to be adhesively laminated with two layers of rotor iron cores 14, 16, and the side surface of the rotor iron core 14 is arranged opposedly to a stator 9 through a screen plate 10 to give an enclosed deep groove type property to the rotor. The rotor iron core 16 is fixed integrally with a drive gear 4 and a clearance between the side surface of the gear and the iron core is made small so that the iron core together with a driven gear 3 reduces oil leakage from the discharge side.