Abstract: [Object] To provide a wire-harness use composite wire having a further improved corrosion resistance, while having excellent conductivity and strength. [Solving means] A wire-harness use composite wire comprising a first element wire which comprises 0.01-0.25 mass % C, 0.01-0.25 mass % N, 0.5-4.0 mass % Mn, 16-20 mass % Cr, 8.0-14.0 mass % Ni, and the balance of Fe and impurities and satisfies that a C+N content is in the range of 0.15 mass %?C+N?0.30 mass %, and a second element wire comprising at least one material selected from the group consisting of copper, copper alloy, aluminum, and aluminum alloy, the first element wire and the second element wire being twisted together.