Abstract: A screw-type closure device comprising a safety cap having a guarantee strip which includes a first ring connected to the bottom of a cap skirt by connecting bridges and a second ring assembled on the first ring by a peripheral zone of reduced thickness which allows the second ring to turn up inside the first ring. The second ring may be divided into at least two independent segments which are separated by gaps. The first ring of the guarantee strip includes at least one oblique groove of reduced thickness opposite one of the gaps in the second ring and which is torn to severe the guarantee strip from the container when the cap is removed.