A wire conductor for a wiring harness includes a stranded wire obtained by twisting strands around a core wire. The core wire is composed of beryllium copper and the strands twisted around the core wire are composed of annealed copper. Preferably, the wire conductor includes a stranded wire obtained by twisting 6, 12 or 18 strands around the core wire. Half of the strands twisted around the core wire are composed of beryllium copper, the remaining strands and the core wire are composed of annealed copper, and the strands composed of beryllium copper and the strands composed of annealed copper are alternately arranged around the core wire. The wire conductor has sufficient conductivity and strength, causes no disconnection even when produced in a small diameter, and has appropriate flexibility.