<p>A grasping member (4) composed of a first linear section (17), a returning section (18) and a second linear section (19) is constituted by bending a center portion of a wire in a longitudinal direction. The first linear section (17) is inserted into a first tube section (13) of a guide member (2), and the second linear section (19) is inserted into a second tube section (14). The first linear section (17) and the second linear section (19) are provided with a first operating section (20) and a second operating section (23). The first linear section (17) and the second linear section (19) of the grasping member (4) are protruded from a leading end portion of a guide tube (10) and a loop (3) is formed. The shape of the loop (3) is changed and enlarged by protruding the second linear section (19) from the leading end portion of the guide tube (10) longer than the first linear section (17).</p>
