A cassette coil comprising an insulator bobbin including a core tube around which a wire coated with an insulating film is wound, forming a coil, and a pair of plate-shaped flanges provided at both ends of the core tube, the flange including a cutout portion opening in a side, wherein the cassette coil includes an insulation wall between a winding start part which is one end of the coil of the wire and an outermost wire part located on the outermost side of the coil of the wire and close to the flange.