A locking device (1) for locking a cap (100) on a container (101) with a flange (102), comprising a lid (2) housing a bushing (4) provided with lower inner notches (42) supported under said flange (102) and outer notches (44) engaging with a groove (22) in the lid (2) to secure said bushing (4) to said lid (2), said lid (2) comprising a severable frangible zone (ZI), said bushing (4) being formed by a ring extended by lugs (41) intended to surround said cap (100) and provided with at least one deformable and severable bridge (45) provided opposite said lugs (41) and capable of being elastically deformed radially to allow the forced insertion of said flange (102) into said bushing (4) and of being broken to allow the removal of said bushing (4) relative to said flange (102) followed by the removal of said cap (100) from said container (101).
