A high-frequency line structure includes a multi-layered resin substrate in which insulating layers of a resin are laminated. A high-frequency-signal input part is arranged on the resin substrate to input a high-frequency signal and supply the high-frequency signal to the resin substrate. A high-frequency-signal output part is arranged in the resin substrate to receive the high-frequency signal from the input part and output the received high-frequency signal. A first metal layer is arranged to encircle the input and output pads and electrically insulated from the input and output parts. A second metal layer is arranged on the resin substrate. A plurality of penetration vias are arranged in the resin substrate to encircle the input part and the output part, and each penetration via being connected to the first and second metal layers.