Vacuum carburizing furnace and vacuum carburizing treatment method

A vacuum carburizing furnace, comprising

• a heating chamber in which a vacuum carburizing treatment is performed on a workpiece to be charged from outside the furnace;
• a charging port for the workpiece, the charging port provided at a bottom portion of the heating chamber;
• an elevator that is arranged below the heating chamber and charges the workpiece into the heating chamber from the charging port;
• a support table that supports the workpiece;
• a lid body provided below the support table, the lid body that covers the charging port;
• an opening/closing detection mechanism that detects opening and closing of the charging port;
• and
• a control device that controls the elevator, wherein
• the elevator has a configuration that raises and lowers the lid body,
• the lid body has a shape that, when raised, comes into close contact with a bottom portion of the heating chamber to close the charging port, and
• the control device is configured to perform control to raise the elevator and raise the lid body when the opening/closing detection mechanism detects that the charging port is opened at an unprescribed timing.