A gas purge device for a metallurgical melting vessel includes a conically shaped ceramic body (2) in contact at its top side with heat contained in the melting vessel. The ceramic body has a static external element and an internal element axially movable therein. A pneumatic drive axially moves the internal element to and fro relative to the external element between a closed position and an open position. The spring force of a spring retains the internal element in the closed position. The device furthermore includes a gas-tight enclosed volume arranged at the bottom side of the ceramic body the volume being connected to a gas supply duct for introduction of purge gas. A deformable membrane is connected to the internal element with the pressure difference between the purge gas pressure prevailing in the gas-tight enclosed volume and the ambient pressure acting upon the membrane.