A central conductor assembly for use in a non-reciprocal circuit comprising a first inductance element between a first input/output port and a second input/output port, and a second inductance element between the second input/output port and a ground port, a magnetic substrate being integrally provided with a first central conductor constituting the first inductance element and a second central conductor constituting the second inductance element; and the second central conductor being crossing the first central conductor on a main surface side of the substrate via a magnetic layer or a dielectric layer, with at least one end portion thereof bent such that high-frequency current flows therethrough in the same direction as or in an opposite direction to that of high-frequency current flowing through the first central conductor.