A vertebral fixing system comprising a connecting part with two longitudinal elements coupled to each other at a first end and having mutually facing recesses for receiving a rod. A portion of a flexible ligature extends through orifices of the two longitudinal elements to define a loop opposite two free ends of the flexible ligature. The two longitudinal elements are engaged at a second end of the connecting part via a locking means. When the two longitudinal elements of the connecting part are locked at the second end of the connecting part, two strands of the flexible ligature are pinched between the rod and a wall of the mutually facing recesses of the two longitudinal elements of the connecting part, preventing the flexible ligature from moving in translation relative to the connecting part.