Provided are a bone fixation screw apparatus and a fastening method thereof. More particularly, provided are a bone fixation screw apparatus and a fastening method thereof including a bone screw which is inserted to a lower side of a receiving portion and has a spherical head formed at a proximal end, a collect chuck which is inserted to an upper side of the receiving portion to be connected with the spherical head of the bone screw inside the receiving portion, and a rod which is seated on an upper side of the collet chuck and fixed through a fixing screw fastened to the receiving portion, in which the bone screw and the collet chuck are introduced to the receiving portion in opposite directions to each other. Therefore, it is possible to firmly and easily fasten the bone screw and the collet chunk and prevent the bone screw from being easily separated by external force.