A pedicle screw has quadruple screw threads capable of moving forward a long distance in a bone upon rotation. For a screw to be embedded in a dense cortical bone of a vertebra, the threads include relief screw threads, to strongly couple with bone tissue in the cortical bone. For a screw to be embedded in a cancellous bone of the vertebra, two lines of threads (odd or even) include relief screw threads while the other two lines of threads include intaglio screw threads, thereby more strongly coupling with relatively soft cancellous bone tissue. The threads are provided in the whole pedicle screw, to move forward at 4-fold higher speed than a single screw thread, and intaglio screw threads are formed at a position to which the cancellous bone is fixed, so that cancellous bone tissues penetrate between the intaglio threads, thereby strongly coupling to the cortical and cancellous bones.
