The vacuum dryer includes: a first half chamber having a first opening, and a drying table on which a workpiece is fixed and positioned at a drying phase; a second half chamber having a second opening and coupled with the first half chamber to form a hermetic chamber; a first moving device that moves the second half chamber relative to the first half chamber between a separated position and a coupled position; a first volume adjusting body disposed in the second half chamber and having a shape that does not collide with the workpiece and the drying table when the drying table is positioned at the drying phase and the second half chamber is located at the coupled position; and a vacuum pump.