A method of connecting feeding lead wires to the winding of a rotor core which can rotate inside a stator with a clearance between the rotor core and the inner surface of the stator, using a joint conductor between the lead wire and the stator winding. Forming on the feeding lead wire, a first part to be connected to the joint conductor, a second part which is thinner than the first part, and a third part which is between the first and second parts and has a thickness changing from the thickness of the first part to the thickness of the second part, and welding the first part to the joint conductor by electron beams or brazing the first part to the joint conductor while cooling the first part.