Provided is a medical screw which can be readily extracted from bones after fusion of bone fractures or at replacement of the screw. The medical screw 11 has a screw thread 11b extending on the outer surface of a distal end portion of the screw 11 and an inner reverse thread extending on the inner surface of a proximal end portion 11d of the screw 11 and made in the opposite direction to the thread direction of the screw thread 11b. An outer reverse thread at a distal end portion of the removal jig 17 is engaged with the inner reverse thread of the screw 11, while being rotated in the opposite direction to the thread direction of the screw thread 11b. This engagement integrates the screw 11 with the removal jig 17. The removal jig 17 is then rotated in the opposite direction to the drilled direction of the screw 11 to detach the screw thread 11b of the screw 11 from the bone fractured region D.
