PURPOSE: To perform transmission of signals and the electric power in a non- contact state by adding the capacity coupling polar plates and the communication channels to 1st and 2nd coupler main bodies respectively which are connected rotatably to each other.

CONSTITUTION: When coupler main bodies 11-1 and 11-2 are rotating with each other, the electric power PI is supplied to a 1st communication circuit 13-1 from the 1st coupler main body 11-1. The circuit 13-1 acquires its own power supply from the power PI and also sends this power PI to a 2nd communication circuit 13-2 via capacity coupled polar plates 14-1, 14-2, 15-1 and 15-2. While the circuit 13-1 receives an input signal SI1 and sends this signal to the circuit 13-2 via said plates 14-1∼15-2. At the same time, an input signal SI2 received from the main body 11-2 is also outputted in the same way as an output signal SO1 of the main body 11-1.