The purpose of the present invention is to provide an electric power supply system that is superior to conventional systems.

This electric power supply system has a configuration in which: a fixed member 8 is provided with an inner conductor 9 arranged along the axial direction of the fixed member 8, an outer conductor 13 arranged along the axial direction of the fixed member 8 so as to cover the inner conductor 9, and a high-frequency conductive path dielectric 5 disposed between the inner conductor 9 and the outer conductor 13; a rotating member 7 is provided with an inner conductor 9 arranged along the axial direction of the rotating member 7, an outer conductor 13 arranged along the axial direction of the rotating member 7 so as to cover the inner conductor 9, and a high-frequency conductive path dielectric 5 disposed between the inner conductor 9 and the outer conductor 13; a high-frequency electric power source 27, the outer conductor 13 of the fixed member 8, the outer conductor 13 of the rotating member 7 and a load 26 are electrically connected so that it is possible to supply electric power from the high-frequency electric power source 27 to the load 26; and the fixed member 8 and the rotating member 7 are combined to form an electromagnetic wave attenuation structure for attenuating the electromagnetic waves emitted from the electric power supply system.