Abstract: An iron core for a rotary electric machine suitable for use as stator iron cores of AC generators for vehicles, for example, winding an iron core blank of strip form and joining convolutions of the spirally wound iron core blank together by electric resistance winding. The spirally wound iron core blank has a plurality of circumferentially spaced apart projections on one surface and a plurality of circumferentially spaced apart recesses on the other surface in positions corresponding to the projections on the one surface. The projections and recesses coincide in position when the iron core blank is spirally wound and convolutions thereof are superposed one above another. The provision of the projections and recesses enables winding of the iron core blank into a spiral form and welding of the convolutions of the spirally wound iron core blank to be effected economically and with increased accuracy.