To steadily hold a screw by arranging/forming plural screw head part gripping holding pieces to lock so as to be lockable/releasable on a screw head part in a petal shape when viewed from the tip side in an outer cylinder body fitted around a tip part of an inner cylinder body so as to be freely slidable in the axial direction and freely rotatable around the axis.

A first outer cylinder body 3 fitted around a tip part of an inner cylinder body 2 so as to be freely slidable in the axial L direction and freely rotatable around the axis L, is provided. Plural screw head part gripping holding pieces 14... to lock so as to be lockable/releasable on a screw head part, are arranged/formed in a petal shape when viewed from the tip side in this first outer cylinder body 3. At using time, when the screw head part is pushed in from the tip side of the first outer cylinder body 3, after the screw head part gripping holding pieces 14... are elastically deformed in the breaking direction, the screw head part is fitted to the inside of the screw head part gripping holding pieces 14..., and the screw head part gripping holding pieces 14... are restored. As a result, inclined face parts 15 of the screw head part gripping holding pieces 14... come into contact with a taper surface of the screw head part. Therefore, a screw can be steadily held on the axis of a pit 1.