Method of manufacturing coil, coil, and electric motor

A method of manufacturing a coil, comprising:

• forming a winding portion extending twisting around an axis along a direction of the axis, the winding portion having a spiral shape such that an outer dimension of the winding portion as viewed in the direction of the axis gradually decreases, the winding portion including a portion in an extending direction of the winding portion, the portion being a deformation allowing portion having a lower rigidity than other portion;
• forming an insulation film on the winding portion over the extending direction of the winding portion;
• and
• compressing the winding portion on which the insulation film is formed, in the direction of the axis, such that the winding portion has a flat shape,
• wherein the winding portion has the spiral shape such that the outer dimension of the winding portion as viewed in the direction of the axis gradually decreases, with none of a portion of the winding portion overlapping another portion of the winding portion.