The invention relates to a child safety closing device (1) associated with a container (2), operating according to a design of two plugs (3, 4) embedded into each other, and allowing a vertical translation movement of the outer plug (4) relative to the inner screw-threaded plug (3) providing an unscrewing possibility and fitted with a first-opening indicator ring (5) connected by breakage bridges (8) to the outer plug (4) capable of vertical translation movement, characterized in that: a) said ring (5) has on its inner surface notches (9) for preventing its rotation when unscrewing the device by interaction with corresponding notches (10) formed on the neck of the associated container inside a peripheral groove (11) outside said collar, in order to induce the braking of the bridges by shearing; b) the upper wall of the groove (11) defines a guiding shoulder (12) for said ring (5) during the vertical translation movement of the ring (5) when connected to the outer plug; c) the notches (10) inside the groove (5) have a height such that they interact with the notches (9) inside the inner face of said ring (5) whatever the position of said ring (5) during the vertical translation movement thereof when connected to the outer plug (4).