Abstract: An improved structure of an anti-burglar screw bolt having a pad and a nut, the bolt including a bolt head and a bolt shaft, characterized in that the bolt head is hexagonal with the inner edges being arranged with equal angle and provided with sloping faces continuing from one to another, and connection region of each of the sloping faces being a blocking face having a high-low depression, the pad being flat and circular having a diameter equivalent to the largest diameter of the bolt head, the center of the pad being provided with a through hole having a hole diameter larger than that of the bolt shaft, one face of the pad being formed into a continuing sloping face corresponding to the sloping face of the individual bolt head, the other face of the pad being provided with a plurality of equally arranged sharp engaging straps, each of the strap having an upright face and a sloping face, the sloping direction of the sloping face being similar to that of the continuing sloping face of the pad, the nut being h