To provide an anchor bolt capable of improving earthquake resistance through the improvement of retention yield strength of a column by enlarging the effective/shank cross-sectional area ratio of the anchor bolt to increase the elongation of a shank at the rupture of a fastening external screw part, thereby increasing absorbed energy until the rupture of the fastening external screw part.

The effective diameter de of a fastening external screw part 11A formed at the axial end part of a shank 10 by thread rolling is set to a value not smaller than the outer diameter dr of the shank 10 to enlarge an effective/shank cross-sectional area ratio Ra. This results in increasing the elongation L of the shank 10 at the rupture of the fastening external screw part 11A.