Abstract: The invention relates to an opening device for packaging containers that comprises at least one base element, which is placed on an opening of the container and which, in particular, completely surrounds the edge area of the opening on the outside and/or inside of the container. The opening device also comprises a covering element, which can be placed on the base element in order to cover the opening of the container. Said covering element has joining means for joining the covering element to the base element once the base element has been placed on the container, and has functional means for performing a predetermined function. The covering element advantageously comprises snap, detent, clamping, hinged or screw joining means for joining to the base element and, as a functional means, can comprise, for example, a closure part for reclosing the opening, a protective part for protecting the base element or a safety seal, which is irreversibly changed the first time the packaging container is opened.