To reduce the warp or deformation of a coil, which is constituted by winding an enamel wire in extremely fine size plural times, by improving rigidity and to enable improvement in dimension accuracy and shape accuracy by rolling the coil.

A self-fusing enamel wire 2 in extremely fine size is used and wound into rectangular roll for five turns, for example, and the coil is heated by blowing hot air so that wires are fused. The main body part of coil, with which the wires are fused like this, is rolled by a presser or roller except a non-rolling part 3 across a winding start terminal part 31 and winding end terminal part 32 of the self-fusing enamel wire 2 so as not to reduce the inter- wire electric insulation of self-fusing enamel wire 2 at the crossing part because of rolling. In such a case, the self-fusing enamel wire 2 is rolled so that the ratio of thickness and width after rolling can be less than '4' in order to prevent the reduction of electric insulation. The non-rolling part 3 crossing the terminal parts 31 and 32 is not rolled or just rolled less than the half of the main body part.