The invention relates to a closure device (1) for a container (2) comprising a container opening (3), wherein the closure device (1) comprises a lid element (4) for closing the container opening (3), an inner housing (5) and a chamber (6) arranged on the lid element (4), wherein the chamber (6) is arranged at least partially in the inner housing (5), wherein the inner housing (5) has a first thread (10) which corresponds positively to a thread (10) of the container (2), wherein lid element (4) and inner housing (5) have second threads (11) corresponding positively to one another along which the lid element (4) is movable relative to the inner housing (5) from a closed position into a discharge position in which discharge position a medium stored in the chamber (6) can exit into the container (2). For the usage-advantageous further development of a closure device of the type in question, it is proposed that the first thread (10) and the second thread (11) are configured opposite to one another in such a manner that during a movement into the discharge position the chamber (6) is moved further into the inner housing (5).