Electric wire conductor, covered electric wire, and wiring harness

A wiring harness comprises a first covered electric wire, and a second covered electric wire. The first covered electric wire comprises a first electric wire conductor made of aluminum or an aluminum alloy and an insulator covering the first electric wire conductor. The first electric wire conductor comprises a wire strand of a plurality of elemental wires twisted together, and has a flat portion where a cross-section of the wire strand intersecting an axial direction of the wire strand has a flat shape. The second covered electric wire comprises a second electric wire conductor made of copper or a copper alloy and an insulator covering the second electric wire conductor. The second electric wire conductor has a lower flatness and a smaller conductor cross-sectional area than the first electric wire conductor of the first covered electric wire.