A coil (1A, 1B, 1C) comprising: a first winding wire which is composed of a single wire or a plurality of wires, and is wound about a winding shaft axis (C 1A, C 1B, C 1C, C 30) to form a first winding (10A, 10B, 10C); and a second winding wire which is composed of a single wire or a plurality of wires, and which is wound coaxially with the first winding wire so as to be in intimate contact with an outer circumferential portion of the first winding to form a second winding (20A, 20B, 20C), wherein at least in the first winding among the first winding and the second winding, one side (11A, 21A, 11B, 21B, 11C, 21C, 31) of a winding wire is wound from an inner circumferential side to an outer circumferential side as a spiral winding, the other side (12A, 22A, 12B, 22B, 12C, 22C, 32) of the winding wire is drawn forth from the inner circumferential side to the outer circumferential side, while crossing the one side (11A, 21A, 11B, 21B, 11C, 21C, 31) of the winding wire, characterized in that the other side (12A, 12B, 12C, 32) of the winding wire in the first winding is wound in a state in which two wires are arranged side by side in a diametrical direction, while at portions where the one side (11A, 11B, 11C, 31) of the winding wire and the other side (12A, 12B 12C, 32) of the winding wire do not cross, the one side (11A, 11B, 11C, 31) of the winding wire in the first winding is wound in a state in which the two wires are piled up in the direction of the winding shaft axis (C 1A, C 1B, C 1C, C 30), and at portions where the one side (11A, 11B, 11C, 31) of the winding wire and the other side (12A, 12B, 120, 32) of the winding wire cross, the one side (11A, 11B, 11C, 31) of the winding wire in the first winding is wound in a state in which the two wires are arranged side by side in the diametrical direction, and a thickness in crossing portions of the one side (11A, 11B, 11C, 31) of the first winding wire and the other side (12A, 12B, 12C 32) of the first winding wire in a direction of the winding shaft axis (C 1A, C 1B C 1C, C 30) is equal to a thickness in other portions. a first winding wire which is composed of a single wire or a plurality of wires, and is wound about a winding shaft axis (C 1A, C 1B, C 1C, C 30) to form a first winding (10A, 10B, 10C); and a second winding wire which is composed of a single wire or a plurality of wires, and which is wound coaxially with the first winding wire so as to be in intimate contact with an outer circumferential portion of the first winding to form a second winding (20A, 20B, 20C), wherein at least in the first winding among the first winding and the second winding, one side (11A, 21A, 11B, 21B, 11C, 21C, 31) of a winding wire is wound from an inner circumferential side to an outer circumferential side as a spiral winding, the other side (12A, 22A, 12B, 22B, 12C, 22C, 32) of the winding wire is drawn forth from the inner circumferential side to the outer circumferential side, while crossing the one side (11A, 21A, 11B, 21B, 11C, 21C, 31) of the winding wire, characterized in that the other side (12A, 12B, 12C, 32) of the winding wire in the first winding is wound in a state in which two wires are arranged side by side in a diametrical direction, while at portions where the one side (11A, 11B, 11C, 31) of the winding wire and the other side (12A, 12B 12C, 32) of the winding wire do not cross, the one side (11A, 11B, 11C, 31) of the winding wire in the first winding is wound in a state in which the two wires are piled up in the direction of the winding shaft axis (C 1A, C 1B, C 1C, C 30), and at portions where the one side (11A, 11B, 11C, 31) of the winding wire and the other side (12A, 12B, 120, 32) of the winding wire cross, the one side (11A, 11B, 11C, 31) of the winding wire in the first winding is wound in a state in which the two wires are arranged side by side in the diametrical direction, and a thickness in crossing portions of the one side (11A, 11B, 11C, 31) of the first winding wire and the other side (12A, 12B, 12C 32) of the first winding wire in a direction of the winding shaft axis (C 1A, C 1B C 1C, C 30) is equal to a thickness in other portions.