The present invention provided a simple-structured metal fitting for joining members to each other, using the less number of component parts and enabling to transmit stresses of both compressive forceand tensile force, and also a joint structure as well as a joining method using the joint metal fitting. The metal fitting 1 for joining members to each other connects a vertical frame member 11 of an upper floor and a vertical frame member 11 of a lower floor, so as to transmit the compressive force and the tensile force. The metal fitting 1 for joining the members to each other is long enough to be extended longitudinally over the vertical frame member 11 of the upper floor and the vertical frame member 11 of the lower floor, directly to which the connecting parts 3 provided on the respective opposite end parts of the metal fitting are connected. The connecting parts 3 of the joint metal fitting 1 placed on the upper and the lower floors respectively are abutted on the vertical side faces of the vertical frame members 11 of the respective floors, and are secured by drill screws 24 driven laterally from the connecting part 3 to the vertical frame member 11. Also, the metal fitting 1for joining the members to each other is used in the joining method.