To execute high-speed communication processing only in a certain local range of a board, and to reduce interference to the outside of the local range of the board.

This millimeter wave transmission device waves includes: a signal generating unit 21 that generates a millimeter wave signal by the signal processing of an input signal Sin; a coupling circuit 205 that transmits an electromagnetic wave S' based on the millimeter wave signal that is generated by the signal generating unit 21 to one end of a board 10; a coupling circuit 207 that receives the electromagnetic wave S' based on the millimeter wave signal from the other end of the board 10; and a signal generating unit 22 that generates an output signal Sout by the signal processing of the millimeter wave signal based on the electromagnetic wave S' that is received by the coupling circuit 207. Preferably, the board 10 is formed of a dielectric material with a relatively large dielectric loss tangent, and a transmission line 206 that functions as a millimeter wave transmission path is constituted within the board 10. By this structure, extremely high-speed signals can be transmitted through the board 10 having a prescribed dielectric constant representing a large loss.