To provide chuck be able to surely hold a torque shear type high power bolt and to attach it simply in connection between beam and square steel pipe column with the torque shear type high power bolt.

Chuck has a claw portion (1) for holding edge of torque shear type high power bolt, metal ring (2) to close nail portion (1) and wire type guide portion (3), which is connected to edge of claw portion (1) and is also longer than the width of a square steel pipe column. The claw portion (1) and guide portion (3) may be made with piano wire material or integrally melded with a hard synthetic resin which has abrasion-resistan character and elasticity. It is better that whole length of guide portion is curved mildly.