A wire harness includes a group of first electric wires connected to a first circuit and a group of second electric wires connected to a second circuit whose consumption current is smaller than that of the first circuit. The group of first electric wires include aluminum electric wires. The group of second electric wires include a large diameter electric wire having a conductor formed of aluminum or aluminum alloy, a small diameter electric wire having a conductor formed of copper or copper alloy and a cross-sectional area of the conductor thereof smaller than that of the large diameter electric wire, and an extra fine electric wire having a conductor formed of the copper or copper alloy and a cross-sectional area of the conductor thereof smaller than that of the small diameter electric wire.