Abstract: A vacuum furnace for heat treatment comprises a heating furnace proper, pre-exhaust chambers, one adapted to feed a workpiece into the furnace proper therefrom and the other adapted to discharge the workpiece out of the oven proper thereinto, vacuum valves for partitioning between the oven proper and the respective pre-exhaust chambers, and a line assembly for deliver of the workpiece from the feed chamber into the discharge chamber through the furnace proper. A heating chamber forming part of the furnace proper is positioned on the upper part above the deliver line assembly, and an externally operable elevating means is disposed in the furnace proper. The work pieces carried by the delivery line assembly, and lifted to the heating chamber where it is heated.