The objective of the present invention is to provide a waveguide and resonator capable of suppressing the energy loss due to the skin effect. A conductive material layer is formed in the vicinity of an inside tube in the region between an outside tube and the inside tube which share the central axis and are made of a conductive material. A spacer layer (space) is formed between the surface of the inside tube and the conductive material layer. In the spacer layer, the end is thicker than the center in the layered body of the spacer layer and the conductive material layer. With the provision of such a layered body, the energy loss due to the skin effect can be suppressed. The effect becomes more prominent with a larger difference of the thickness of the spacer layer between the center and the end.