A flexible substrate (1) is bent at a bending part (2). A dielectric plate (3) has first and second main surfaces opposite to each other. A high-frequency signal line (4) is provided on the first main surface of the dielectric plate (3). A ground conductor (5) is provided on the second main surface of the dielectric plate (3). The high-frequency signal line (4) and the ground conductor (5) form a micro strip line. A local absent part (6) facing the high-frequency signal line (4) is provided on the ground conductor (5) only at the bending part (2).