Abstract: A device adapted to transmit a signal and a power with an electromagnetic wave or light being as the transmission medium. This device comprises active and passive modules each provided with means for effecting transmission and reception of at least one of the electromagnetic wave or light, and a signal processing circuit. Each module may further comprise an output or frequency control circuit. One of these modules is provided at a moving body such as a rotary body, and the other is provided at a fixed body to effect both signal transmission and power transmission between the moving and fixed sides.