The invention relates to a stopper device (50) comprising a stopper (51) and a cap (52) consisting of a plastic material and having a ring (53) provided with tabs (537) for locking onto the neck (12) of a container (1) and a body (54) for handling the ring said body being provided with first means (5464) for transmitting a thrust force (E"2) to the ring and second means (541) for activating the locking tabs (537). The ring (53) and the handling body (54) are respectively provided with first retaining means (535) and second retaining means (5464) that hold the handling body (54) in a waiting position. The handling body (54) is mobile parallel to the direction of the thrust force (E"2) and in relation to the ring (53), between a first position wherein it activates the locking tabs (537) of the ring and is mobile in translation only in the direction of the thrust force (E"2), and a second position wherein it also activates the locking tabs (537) and is immobilised in relation to the ring in axial translation. The handling body comprises a first surface (5465) and a second surface (5466), that are cylindrical with a generatrix or in the shape of a truncated cone respectively arranged facing the first means (535) for retaining the ring (53) and the locking tabs (537), on the course of travel of the handling body (54) between its first and second positions. Said locking tabs (537) extend from a continuous edge of the ring and are each arranged in an opening with a closed contour.
