A tube which includes: a tube body portion through which a fluid flows; a protector portion having an interior hollow space in which the tube body portion is provided, and an exterior wall defining the interior hollow space and having a flat outer surface; and a supporting portion supporting the tube body portion inside the hollow space in a position spaced from an inner surface of the hollow space. The supporting portion extends from the exterior wall of the protector portion in a direction substantially perpendicular to the flat outer surface of the exterior wall and across the hollow space to support the tube body portion at a middle portion thereof.