1 assumes a contracted state by the spring force thereof in its natural state such that the raised portions 3 and 4 are spaced from each other the raised portions 3 and 4 are caused to come close to each other so that the clamping body 1 assumes a spread state a holder 2 is then attached to the clamping body 1 so as to straddle the raised portions 3 and 4 whereupon the clamping body is held in the spread state the holder 2 is formed into an inverted u shape and has a width as large as or smaller than the clamping body 1 the holder 2 has a knob 6 protruding from a central top thereof the knob 6 is gripped by a suitable tool so that the holder 2 is pulled out a positioner a will now be described the positioner a is made of a synthetic resin and includes a clamp retainer 7 to which the hose clamp c is attached a detent 8 preventing a circumferential displacement of the hose clamp c relative to the hose h and hooks 9 preventing an axial displacement of the hose clamp c relative to the hose h the clamp retainer 7 has substantially the same width as the clamping body 1 and is formed into a generally semi circular shape so that the clamping body 1 in the spread state is inset through an upper opening 10 into the retainer the clamp retainer 7 is flexible so that the opening 10 is spread thus the clamp retainer 7 is spread when the clamping body.