To provide a new automatic stacking device for a formed cylindrical duct capable of quickly carrying it out by automatically stacking delivered formed cylindrical dusts in a loading carriage.

In this automatic stacking device for a formed cylindrical duct, long/short formed cylindrical ducts to be delivered having a large-diameter/small-diameter are guided onto a horizontally raised guide plate through an inclined base and an upward-stretched conveyor in order, and the cylindrical ducts are automatically stacked inside a stacking carriage positioned directly under the cylindrical duct by lowering rotation or horizontal downward movement of the guide plate, and the stacked cylindrical ducts are carried out by the stacking carriage.