PROBLEM TO BE SOLVED: To surely prevent the generation of a bone cavity by stably holding, within a hollow screw, a filling material filled into the inside of the screw.SOLUTION: An osteosynthesis tool 10 is provided which includes a screw 3 made of a biodegradable material and a restriction member 4 made of a biodegradable material. The screw 3 includes a body part 1 and a tubular head part 2. The body part 1 has a spiral thread formed on the outer circumferential surface of the body part and a hole 1a which is formed in a length direction and is opened at least in one end and is to be filled with a filling material. The tubular head part 2 is provided in one end of the body part 1 and causes the hole 1a to communicate with the outside in the length direction. The restriction member 4 can be mounted to the head part 2 and restricts the length-direction movement of the filling material filled into the inside of the hole 1a.
