An electric wire conductor having both flexibility and a space-saving property, a covered electric wire, and a wiring harness containing such an electric wire conductor. The electric wire conductor contains a plurality of elemental wires twisted together, and has a non-circular portion in which a cross section intersecting an axial direction of the wire strand has a non-circular shape. The cross section of the non-circular portion has a continuous vacancy capable of accommodating two or more of the elemental wires. Further, a covered electric wire contains the electric wire conductor and an insulator covering the electric wire conductor. Furthermore, a wiring harness contains the covered electric wire.