To provide a method for joining a covered wire to a base material without removing the coating preliminarily.

Both members, a covered wire 1 consisting of a copper core wire and a coating of a dielectric material (e.g. polyamideimide resin) and a copper base material 2 for joining, are superimposed on each other, put between two electrodes 3 abutting on each member 1, 2, pressurized through the two electrodes 3 by a pressurizing device 6, and applied with a high frequency voltage by means of a high frequency power source 4; consequently, the coating of the dielectric material is first deteriorated through dielectric heat generation and broken by pressure; and then, the core wire of the conducting covered wire 1 and the joining base material 2 are resistance-heated and pressure-welded.