A shield conductor Wa comprises: a metallic pipe 20, a wire 10 to be inserted into the pipe 20, and a groove-like fitting member 22 provided in the pipe 20 as extending along the direction of axis of the wire 10, and at the same time, attached tightly to the circumference of the wire. With the inner surface of the groove-like fitting member 22 in the pipe 20 attached tightly to the circumference of the wire 10, the heat generated in the wire 10 is transmitted directly to the pipe 20, and then released to the air from the circumference of the pipe 20. This improves radiation performance of the shield conductor Wa.