A high-frequency wire (1) comprises a conductor (10) which is formed by compressing a plurality of core wires (11) wherein the outer circumference sides of wire materials (11a) formed from insulating resin are covered with a metal layer (11b), and a sheath (20) which is disposed upon the conductor (10). Each core wire (11) of the conductor (10) is compressed such that the deformation rate is greater than 0% and less than or equal to 20%. The compression is carried out, for example, when bundling the plurality of core wires (11) and when working the sheath.