A closure device for attachment to a packaging container, by which the packaging container can be closed in a child-resistant and reclosable manner, wherein the closure device is made of at least 70% of a paper-based material and comprises at least two tabs, at least one slot being formed in a first tab, and a second tab comprising at least one hook element having a locking lug, wherein to close the closure device, the hook element is guided from a rear side of the first tab through the slot to a front side of the first tab, and the locking lug being designed such that, when the hook element is guided through the slot on the front side of the first tab, it comes into contact with an edge-side boundary of the slot in such a way that a return of the hook element through the slot to open the closure device is possible only by a simultaneous displacement of the slot relative to the hook element.