A flex-resistant wire has a conductor portion configured as a multiple-stranded wire. The multiple-stranded wire has a plurality of bunched strands that are twisted together. Each of the bunched strands has a plurality of conductors that are twisted together. In each of the bunched strands, the lay length of the conductors that are twisted together is at least 10 times greater than a strand diameter of the bunched strand but not greater than 47.2 times the strand diameter. The lay length of the bunched strands that are twisted together is at least 5 times greater than a pitch diameter of the multiple-stranded wire but not greater than 30 times the pitch diameter. The lay length of the conductors is smaller than or equal to the lay length of the bunched strands. The flex-resistant wire may be provided as one of the wires forming a wire harness.