The present invention relates to a bone distractor for controlling the relative position and rotation angle of two bone fragments during distraction osteogenesis. The present invention comprises: a first bone plate to be coupled to bone fragments a second bone plate to be coupled to bone fragments, distanced from the first bone plate a nut to which the first bone plate is coupled a lead screw fastened so as to allow the nut to move spirally a universal joint connected to the front end of the lead screw and a rod connected to the universal joint so as to be able to be rotated by an operator. An end cap is coupled to the back end of the lead screw. The second bone plate is coupled to the end cap. An incline plane is formed on the outer surface of the end cap neighbouring the skin to prevent contact with the skin. According to the present invention, it is possible to precisely and conveniently control the relative position and rotation angle of two bone fragments by a joint motion of a universal joint during distraction osteogenesis. In addition, the accuracy and efficiency of distraction osteogenesis can be improved since it is possible to prevent the incline plane of the end cap to be inserted into the skin from coming in contact with the skin, and to prevent the occurrence of necrosis and inflammation by minimizing pressure on the skin.La présente invention concerne un distracteur osseux destiné à commander la position relative et langle de rotation de deux fragments dos au cours dune ostéogenèse par distraction. La présente invention comporte : une première plaque à os appelée à être couplée à des fragments dos une deuxième plaque à os appelée à être couplée à des fragments dos, écartée de la première plaque à os un écrou auquel est couplée la première plaque à os une vis sans fin fixée de façon à permettre à lécrou de se déplacer de manière hélicoïdale un joint universel relié à lextrémité avant de la vis sans fin et une tige reliée au joint universel de faço
