To provide a transmission line less in conductor loss, a high frequency device, and a method of manufacturing the transmission line.

The transmission line 10 for transmitting high frequency signals includes: wiring 103 where a high frequency current induced accompanying the transmission of the high frequency signals is distributed; a ground conductor film 101 disposed facing the wiring 103; and an interlayer film 102 provided at least between the wiring 103 and the ground conductor film 101 and composed of a composite material for which particles 111 comprising a first material are dispersed in a second material 112. The wiring 103 has at least one projection part on a surface facing the ground conductor film 101.