A screw anchor assembly is a screw anchor assembly used in spinal screw fixation, and includes a screw having screw threads in a lengthwise direction, and a screw anchor which is inserted into a predefined position of spine, and has anchor threads on an inner surface defining a receiving part into which the screw is inserted, the receiving part being expanded during screw coupling with the screw, wherein the screw anchor includes a plurality of divisions formed along a lengthwise direction, and has overlapping parts between adjacent divisions in the plurality of divisions.