A wire bar is formed by winding a wire, which comprises a first flat portion formed along an overall longitudinal length, around a peripheral surface of a metal core such that the peripheral surface of the metal core and the first flat portion tightly contact with each other. Since this increases the area size of a contact portion where the wire and the metal core contact each other, it is possible to increase the force of static friction which fixes the wire to the metal core. Fixing of the wound wire to the metal core by the strong force of static friction effectively prevents the wound wire from getting deviated.