A wire harness exterior protecting tube minimizes sagging of a wire harness laid in a straddling manner in a vehicle and allows smooth bending of the wire harness. The wire harness exterior protecting tube has longitudinal opposite ends supported in a straddling manner by the vehicle without support between the opposite ends. The protecting tube has at one side section a vertical flat plate section and also has the other section having a square U-shaped or semicircular ring-shaped cross-section. The other section connects to the one side section to form a square or semicircular cross-sectional shape. That portion of the other section which faces the flat plate section is a bellows section having a corrugated shape. The thickness of the flat plate section is adapted to suppress the sagging of the protecting tube caused by the weight of the wire harness and to be bendable by bending of the bellows.