Composite winding element and the transformer using the same, transformer systems and noise cut filter composite winding element

Disclosed is a composite wound element (Tra) which is used in a transformer or a transformation system, and used as a composite wound element for a noise-cut filter, wherein a plurality of coils (1) are enclosed in a magnetic connection member (2a), and are configured by winding belt-like conductive members (11, 12, 13) so that the width direction of the conductive members (11, 12, 13) corresponds to the axial direction of the coils (1). The transformer, the transformation system, and the composite wound element for a noise-cut filter are provided with the composite wound element having the aforementioned structure. Thus, the composite wound element (Tra), the transformer, the transformation system, and the composite wound element for a noise-cut filter can be produced more easily than ever before.