A dual mode choke coil comprising: - a lower core (4, 41, 42) made of a magnetic substance, in which four columnar bodies (5a-5d) whose respective axes are upright are placed on a quadrilateral square of a flat plate, the columnar bodies (5a-5d) being such that a first columnar body and a second columnar body are arranged in parallel to a third columnar body and a fourth columnar body; - a first coil in which the winding direction of a first coil conductor wound around the first columnar body and the winding direction of a third coil conductor wound around the third columnar body are different to each other, and the first coil conductor and the third coil conductor are connected in series; - a second coil in which the winding direction of a second coil conductor wound around the second columnar body and the winding direction of a fourth coil conductor wound around the fourth columnar body are different to each other, and the second coil conductor and the fourth coil conductor are connected in series; - a first upper core made of a magnetic substance, which is brought in contact with upper portions of the first columnar body and the second columnar body; and - a second upper core made of a magnetic substance, which is brought in contact with upper portions of the third columnar body and the fourth columnar body, - wherein the first upper core and the second upper core are arranged with a gap formed therebetween; and - wherein the winding direction of the first coil conductor and the winding direction of the second coil conductor are different, characterised in that: either a) a cut part is formed in the lower core at a part of the side between the first columnar body and the third columnar body and at a part of the side between the second columnar body and the fourth columnar body, the cut parts being formed in a direction parallel to the gap; or b) a cut part is formed in the lower core at a part of the side between the first columnar body and the second columnar body and at a part of the side between the third columnar body and the fourth columnar body, the cut parts being formed in a direction perpendicular to the gap. - a lower core (4, 41, 42) made of a magnetic substance, in which four columnar bodies (5a-5d) whose respective axes are upright are placed on a quadrilateral square of a flat plate, the columnar bodies (5a-5d) being such that a first columnar body and a second columnar body are arranged in parallel to a third columnar body and a fourth columnar body; - a first coil in which the winding direction of a first coil conductor wound around the first columnar body and the winding direction of a third coil conductor wound around the third columnar body are different to each other, and the first coil conductor and the third coil conductor are connected in series; - a second coil in which the winding direction of a second coil conductor wound around the second columnar body and the winding direction of a fourth coil conductor wound around the fourth columnar body are different to each other, and the second coil conductor and the fourth coil conductor are connected in series; - a first upper core made of a magnetic substance, which is brought in contact with upper portions of the first columnar body and the second columnar body; and - a second upper core made of a magnetic substance, which is brought in contact with upper portions of the third columnar body and the fourth columnar body, - wherein the first upper core and the second upper core are arranged with a gap formed therebetween; and - wherein the winding direction of the first coil conductor and the winding direction of the second coil conductor are different, characterised in that: either a) a cut part is formed in the lower core at a part of the side between the first columnar body and the third columnar body and at a part of the side between the second columnar body and the fourth columnar body, the cut parts being formed in a direction parallel to the gap; or b) a cut part is formed in the lower core at a part of the side between the first columnar body and the second columnar body and at a part of the side between the third columnar body and the fourth columnar body, the cut parts being formed in a direction perpendicular to the gap. a) a cut part is formed in the lower core at a part of the side between the first columnar body and the third columnar body and at a part of the side between the second columnar body and the fourth columnar body, the cut parts being formed in a direction parallel to the gap; or b) a cut part is formed in the lower core at a part of the side between the first columnar body and the second columnar body and at a part of the side between the third columnar body and the fourth columnar body, the cut parts being formed in a direction perpendicular to the gap.