An inventive automated heat treatment system has a furnace for heat treating forged engine valves, a carry-in mechanism for transporting the forged valves into the furnace, and a carry-out mechanism for transporting heat treated valves out of the furnace. Each of the carry-in mechanism and the carry-out mechanism has a retention mechanism for retaining valves hung, and a transport mechanism for transporting valves to the furnace as they are hung. The furnace has heating means, groups of paired rails for supporting and moving the valves hung in the furnace, and a stopper for controlling the positions of the valves on the rails. The engine valves are maintained hung with their umbrella-shaped portions supported by the respective mechanisms throughout the automated heat treatment processes. Thus, the heat treatment of engine valves is done in a fewer steps than in a conventional system.