To provide a method of winding coil around a bobbin, by which the width of a coil can be reduced further, without compromising the shape retaining property and rigidity of a thin coil bobbin, and to provide a coil bobbin used for the method.

In the method of winding coil around a bobbin, a winding (1), having a square cross section, is wound around a coil bobbin (2) while one diagonal line of the cross section is kept perpendicular to the side peripheral surface (20) of the bobbin (2). A preferable coil bobbin, used for the method has projecting linear ribs (21), has a rectangular isosceles triangular cross sections and is formed on the whole or a partial side peripheral surface of the bobbin at intervals which are equal to or twice or more wide of the length of the diagonal line (11). The projection linear ribs (21) can be formed continuously or discontinuously.