Closure element (1) of a container particularly made from foil-type material, in particular of a bag-type container for receiving a liquid substance, the closure element having a base (5) that can be fixed to or is already fixed to the container, and which defines a passage (13) and a lid member (3) mounted to the base (5) to clear and close the passage (13), characterized in that the closing element (1) has a transport state in which the lid member (3) is attached to the base (5) via at least one predetermined breaking point (61), and an installation state in which, after separation of the predetermined breaking point attachment, the lid member (3) can rotate relative to the base (5) from an open position to a locked position in which the lid member (3) is removably held at the base (5) by a detent mechanism.