Abstract: A clamping band equipped with a clamping ear is capable of being reduced in diameter by deforming the clamping ear and of maintaining the reduced-diameter state by the action of a catch section designed to prevent the clamping band from expanding in the direction toward diameter enlargement. With such a structure, the clamping band is not caused to enlarge its diameter even under the action of any force exerted on the member to be clamped in the direction toward expansion, prevents the decrease in sealing ability, and maintains strong clamping force.