A plurality of contacts form a plurality of differential pairs between adjacent contacts of the plurality of contacts. Contact portions of contacts of the plurality of contacts forming each of at least three differential pairs of the plurality of differential pairs are located in a vertical direction at positions at one side in the vertical direction in a plane orthogonal to the axial direction. Also, the at least three differential pairs are arranged in parallel to one another in a state separated from one another by equal distances in a horizontal direction in the orthogonal plane. Contact portions of contacts of the plurality of contacts forming another differential pair other than the at least three differential pairs are located in the horizontal direction at positions at the other side in the vertical direction in the orthogonal plane.