Metering device in particular for metering an additive in the field of oil exploration with a metering element adjustable by an adjusting means. To improve such a metering device in that already with minimal movement of the adjusting means in a constructive simple way a particular amount of additive is added to raw material and also to quickly interrupt the metering, the metering element comprises a metering gap and a valve means arranged behind the metering gap downstream in fluids moving direction.