PROBLEM TO BE SOLVED: To provide a screw for fixing a bone, which uses bioabsorbable resin as material and which does not often cause wrenching-off troubles when fastened and has high torsional strength.SOLUTION: The screw has a screw part where a screw thread is formed, and is for passing through one mass and the other mass and fastening them. The screw is formed by machining a stretched rod in such a way that the axial direction of the screw part matches with the axial direction of the stretched rod, the stretched rod being formed by subjecting a columnar rod of polylactic acid resin to torsional stretching in which the rod is twisted while being hot-stretched, wherein the torsion direction of the columnar rod is the same as the winding direction of the spiral of the screw thread.COPYRIGHT: (C)2012,JPO&INPIT【課題】生体吸収性樹脂を素材とし、締結時にねじ切れするトラブルの少ない、捩じり強度の高い、骨を固定するためのねじを提供することを目的とする。【課題を解決するための手段】ねじ山が形成されたねじ部を有し、一の塊体と他の塊体を貫通して締結するためのねじであって、ポリ乳酸系樹脂の柱状ロッドを軸方向に熱延伸しつつ捩じる捩じり延伸してなる延伸棒を、前記ねじ部の軸方向を前記延伸棒の軸方向と一致させて切削加工してなり、前記柱状ロッドの捩じり方向がねじ山の螺旋の巻き方向と同じであるねじである。【選択図】 図3
