A stud locking tool, equipped with a first clip and a second clip, that can be attached to a stud; wherein the first clip has a first flange, an inner cylindrical portion adjacent to the first flange and having a through hole, and a locking claw formed on the inner cylindrical portion for engaging the stud; and the second clip has a second flange, an outer cylinder portion having an outer cylinder accommodating portion capable of accommodating the inner cylinder portion, and wherein the second clip further comprises a slope portion adjacent to the outer cylinder portion and having a guide surface for guiding the end portion of the stud into the through hole, wherein the inner cylinder portion of the first clip has a large diameter inner cylindrical portion adjacent to the first flange; a small diameter inner cylinder portion adjacent to the large diameter inner cylinder portion, that is smaller in diameter than the large diameter inner cylinder portion; and an inner cylindrical end portion adjacent to the small diameter inner cylindrical portion, having a diameter larger than that of the small diameter inner cylindrical portion; the outer cylinder portion of the second clip has a pair of engagement claws; and the distance opposing the engagement claw bottom surfaces of the pair of engagement claws is smaller than the outer diameter of the inner cylindrical end portion of the first clip, wherein the height direction length of the inner cylinder end portion of the first clip is shorter than the height direction length from the engaging claw bottom surfaces of the engaging claws of the second clip to the bottom surface of the accommodating portion of the outer cylinder accommodating portion, and the first clip is movable by a fixed distance in the height direction from the position where the upper surface of the inner cylinder end portion abuts on the bottom surface of the engaging claws, to the position where the lower surface of the inner cylinder end portion abuts on the bottom of the accommodating portion. an inner cylindrical portion adjacent to the first flange and having a through hole, and a locking claw formed on the inner cylindrical portion for engaging the stud; and the second clip has a second flange, an outer cylinder portion having an outer cylinder accommodating portion capable of accommodating the inner cylinder portion, and wherein the second clip further comprises a slope portion adjacent to the outer cylinder portion and having a guide surface for guiding the end portion of the stud into the through hole, wherein the inner cylinder portion of the first clip has a large diameter inner cylindrical portion adjacent to the first flange; a small diameter inner cylinder portion adjacent to the large diameter inner cylinder portion, that is smaller in diameter than the large diameter inner cylinder portion; and an inner cylindrical end portion adjacent to the small diameter inner cylindrical portion, having a diameter larger than that of the small diameter inner cylindrical portion; the outer cylinder portion of the second clip has a pair of engagement claws; and the distance opposing the engagement claw bottom surfaces of the pair of engagement claws is smaller than the outer diameter of the inner cylindrical end portion of the first clip, wherein the height direction length of the inner cylinder end portion of the first clip is shorter than the height direction length from the engaging claw bottom surfaces of the engaging claws of the second clip to the bottom surface of the accommodating portion of the outer cylinder accommodating portion, and the first clip is movable by a fixed distance in the height direction from the position where the upper surface of the inner cylinder end portion abuts on the bottom surface of the engaging claws, to the position where the lower surface of the inner cylinder end portion abuts on the bottom of the accommodating portion.