Abstract: Device (10) and method to complete reinforcement cages comprising a plurality of longitudinal rods (13) and stirrups (12) separated at intervals along the rods (13). The device (10) is used to position the longitudinal rods (13) in correspondence with the inner corners of the stirrups (12), and comprises supporting means defining a plane (23, 123) which supports a pre-cage (11) comprising the stirrups (12) and the longitudinal rods (13) arranged free within the perimeter of the stirrups (12). One corner of the stirrups (12) rests on, and faces towards the outside of, the plane (23, 123). Lifting elements (25) lift the pre-cage (11) to overturn it partly and in sequence on the plane (23, 123), so as to take on each occasion a different corner of the stirrups (12) into an adjacent position facing towards the outside of the plane (23, 123).