A non-reciprocal circuit comprising: a planar magnetic material; a center conductor formed on a top surface of the magnetic material; a first ground conductor formed on the underside of the magnetic material, and having a plurality of cutouts (5a, 5b, 5c) provided around its periphery; a plurality of input/output terminals (6a, 6b, 6c) formed within portions of the cutouts (5a, 5b, 5c) provided in the first ground conductor on the underside of the magnetic material; a dielectric substrate disposed face to face with the underside of the magnetic material; a second ground conductor formed on a top surface of the dielectric substrate, and having a plurality of cutouts (8a, 8b, 8c) provided in the same places as the cutouts (5a, 5b, 5c) provided in the first ground conductor; a plurality of signal conductors (9a, 9b, 9c) formed within portions of the cutouts (8a, 8b, 8c) provided in the second ground conductor on the top surface of the dielectric substrate; a first connector (10a, 10b, 10c) to electrically connect the center conductor to the plurality of input/output terminals (6a, 6b, 6c); a second connector (11a, 11b, 11c, 16) to electrically connect the input/output terminals (6a, 6b, 6c) and the signal conductors (9a, 9b, 9c) facing each other among the plurality of input/output terminals (6a, 6b, 6c) and the plurality of signal conductors (9a, 9b, 9c), and to electrically connect the first ground conductor with the second ground conductor; and a permanent magnet disposed face to face with the top surface of the magnetic material on which the center conductor is formed, and the second connector is comprised of metal bumps (11a, 11b, 11c, 16). a planar magnetic material; a center conductor formed on a top surface of the magnetic material; a first ground conductor formed on the underside of the magnetic material, and having a plurality of cutouts (5a, 5b, 5c) provided around its periphery; a plurality of input/output terminals (6a, 6b, 6c) formed within portions of the cutouts (5a, 5b, 5c) provided in the first ground conductor on the underside of the magnetic material; a dielectric substrate disposed face to face with the underside of the magnetic material; a second ground conductor formed on a top surface of the dielectric substrate, and having a plurality of cutouts (8a, 8b, 8c) provided in the same places as the cutouts (5a, 5b, 5c) provided in the first ground conductor; a plurality of signal conductors (9a, 9b, 9c) formed within portions of the cutouts (8a, 8b, 8c) provided in the second ground conductor on the top surface of the dielectric substrate; a first connector (10a, 10b, 10c) to electrically connect the center conductor to the plurality of input/output terminals (6a, 6b, 6c); a second connector (11a, 11b, 11c, 16) to electrically connect the input/output terminals (6a, 6b, 6c) and the signal conductors (9a, 9b, 9c) facing each other among the plurality of input/output terminals (6a, 6b, 6c) and the plurality of signal conductors (9a, 9b, 9c), and to electrically connect the first ground conductor with the second ground conductor; and a permanent magnet disposed face to face with the top surface of the magnetic material on which the center conductor is formed, and the second connector is comprised of metal bumps (11a, 11b, 11c, 16).