To provide an inexpensive winder for winding a rectangular wire around a bobbin through a simple arrangement.

A wire guide 5 is provided stationarily at a position corresponding to the middle of a bobbin 3 and an arranging plate 6 for guiding a rectangular wire 2 being wound around the bobbin 3 is provided in order to arrange the rectangular wire. A pair of guide faces inclining at about 45° against the abutting part of the arranging plate 6 on the circumferential surface side of the bobbin is formed in order to support the arranging plate 6 slidably in the axial direction of the bobbin and to urge the arranging plate 6 to the bobbin side gravitationally. Through guide action of the wire guide 5 and the arranging plate 6, the ultrathin rectangular wire 2 is wound in ten layers or more around the bobbin 3 while being arranged tightly in the axial direction of the bobbin.