A coil 4 of the present invention is made by helically winding a wire rod 40. A cross-sectional shape of the wire rod 40 of the coil 4 includes a curved portion 44 that is arcuately curved toward a center axis 300 of the coil 4； a flat portion 45 that is provided on an outer circumference of the coil 4, and is formed in a flat shape with a curvature that is smaller than a curvature R3 of the curved portion 44； and at least one protruding portion 46 that is provided at the boundary between the curved portion 44 and the flat portion 45 or in the vicinity of the boundary, and protrudes toward an adjacent wire rod 40.
