the invention relates to a venting unit for a die casting device which has a mold cavity that is adapted to be filled with liquid casting material and a gas suction device that is connected to the mold cavity for extracting gas from the mold cavity by suction , the venting unit comprising a flow labyrinth , the inlet of which is adapted to be connected to the mold cavity and the outlet of which is adapted to be connected to the gas suction device . in order to develop the venting unit in such a way that it makes improved evacuation of the mold cavity possible without the risk that liquid casting material can escape from the venting unit , it is proposed according to the invention that the flow cross - section of the flow labyrinth is variable . furthermore , a die casting device with a venting unit of this kind is proposed .