An outer cover 16 includes a flexible tube portion 24 having flexibility and an inflexible tube portion 25. The flexible tube portion 24 has a corrugated tubular shape in which concave portions 26 and convex portions 27 both extending in a circumferential direction are alternately formed side by side in an axial direction and in which intervals of the adjacent concave portions 26 or intervals between the adjacent convex portions 27 are partially changed.
