A wire harness includes a main harness that can be commonly installed in a plurality of installation target vehicles, and a branch connection portion that is visually identifiably provided at a predetermined location on at least any one of a communication wire, a power supply wire, a signal wire, and a ground wire of the main harness. An additional connection member, connected to at least one electrical device that is actually installed in one of the plurality of installation target vehicles, is later connectable to the branch connection portion in a branching manner.