A freeze dryer in which a prototype of a vegetable of the present invention is preserved is a freeze-drying apparatus using sublimation in a high vacuum state. The freeze-drying apparatus includes a door to be opened, a product is inserted into the door, a transparent window is formed in the door, A drying chamber in which a drying chamber gas line is formed to dry the product； A cooling chamber gas line is formed in which a vacuum window is opened and a vacuum pump is connected and a cold trap is formed in the door, and a transparent window is formed on the door and a plurality of turns are wound around the outer periphery of the chamber. When the ice is removed and the product is discharged, A cooling chamber in which thawing takes place； A conduit interconnecting the drying chamber and the cooling chamber and having a shut-off valve； The drying chamber is indirectly cooled at the outer periphery of the chamber while the cooling member flows into the drying chamber gas line when the product is frozen, so that the inside of the drying chamber is indirectly frozen to -50 to -40 ° C., The inside of the drying chamber is indirectly heated to 30 to 50 ° C with the heating member flowing in the drying chamber gas line, the internal air pressure is maintained at 0.3 mbar or less； Wherein the cooling chamber operates the vacuum pump so that the internal air pressure of the cooling chamber is kept at 0.3 mbar or less when the product is frozen and the internal air pressure of the cooling chamber is maintained at 0.3 mbar or less at the time of product drying, The interior of the cooling chamber is indirectly frozen to -85 to -55 占 폚 as the cooling member flows into the chamber gas line； Wherein the shutoff valve is closed when the product is frozen, the interior of the drying chamber is indirectly frozen to -50 to -40 占 폚 and the interior of the cooling chamber is maintained at 0.3 mbar or less, and ii) When the inside of the cooling chamber is maintained at -85 to -55 DEG
