High-frequency signal transmission device and high-frequency signal transmission cable

A high-frequency signal transmission cable comprising:

• a dielectric layer having first and second surfaces by which a thickness of the dielectric layer is defined;
• a first wiring layer formed on the first main surface of the dielectric layer, the first wiring layer including at least M (M indicating a natural number of 2 or more) differential transmission lines and at least 2×M first ground lines;
• and
• a second wiring layer formed on the second main surface of the dielectric layer, the second wiring layer including at least M second ground lines;
• wherein the high-frequency signal transmission cable includes at least M signal transmission channels each including one differential transmission line, two first ground lines and one second ground line, said one differential transmission line interposed between said two first ground lines and opposed to said one second ground line, and
• at least two first ground lines belonging to adjacent separate signal transmission channels of said at least M signal transmission channels are interposed between two differential transmission lines belonging to said adjacent separate signal transmission channels.