A vacuum producing device (1) possessing a principal suction nozzle unit (2) with a shut off valve (27) on the upstream side thereof and an additional suction nozzle unit (3) connected in parallel to the principal suction nozzle unit (2). While the supply of pressure medium for the principal suction nozzle unit (2) is controlled in a manner dependent on the negative pressure produced by controlling the shut off valve (27), the additional suction nozzle unit (3) remains (3) constantly in operation. This means that a complete build up of vacuum may be ensured in conjunction with a complete switching off of the principal suction nozzle unit (2) together with a resulting air economizing effect.