A screw for fixing vertebra for letting a patient perform spinal motion more smoothly after a pedicle screw insertion surgery is disclosed. A head portion of the screw body is pivotally joined in sliding contact on the head seat portion of a movable washer, which is also pivotally joined in sliding contact on the washer seat portion of a fastening nut. A first aperture and a second aperture are formed in the fastening nut and movable washer respectively, and an elongating portion without a thread is formed between a screw portion and the head portion of the screw body.
