A vacuum dryer (10, 100, 200) for drying a workpiece, the vacuum dryer (10, 100, 200) comprising: a first half chamber (11, 111, 211) having a first opening (11a, 211a), and a rotatable drying table on which the workpiece is fixed, the drying table configured to be positioned at a drying phase; a second half chamber (15, 215) having a second opening (15a, 215a) configured to be in close contact with the first opening (11a, 211a), the second half chamber (15, 215) configured to be coupled with the first half chamber (11, 111, 211) to form a hermetic chamber; a first moving device configured to move the second half chamber (15, 215) relative to the first half chamber (11, 111, 211) between a separated position and a coupled position, the second half chamber (15, 215) being separated from the first half chamber (11, 111, 211) at the separated position, and the second opening (15a, 215a) being in close contact with the first opening (11a, 211a) at the coupled position; a first volume adjusting body disposed in the second half chamber (15, 215), the first volume adjusting body 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 (15, 215) is located at the coupled position; and a vacuum pump connected to the hermetic chamber; wherein the vacuum dryer (10, 100, 200) comprises a working fluid source; a clamp disposed on the drying table, the clamp having a fluid cylinder, the clamp configured to fix the workpiece to the drying table; a hollow housing disposed to be inserted into the first half chamber; a swivel shaft coupled with the drying table, the swivel shaft configured to rotate with the drying table inside the housing; an annular channel circumferentially located between the housing and the swivel shaft; a first channel located inside the housing to connect the working fluid source and the annular channel; and a second channel located inside the swivel shaft to connect the fluid cylinder and the annular channel. a first half chamber (11, 111, 211) having a first opening (11a, 211a), and a rotatable drying table on which the workpiece is fixed, the drying table configured to be positioned at a drying phase; a first opening (11a, 211a), and a rotatable drying table on which the workpiece is fixed, the drying table configured to be positioned at a drying phase; a second half chamber (15, 215) having a second opening (15a, 215a) configured to be in close contact with the first opening (11a, 211a), the second half chamber (15, 215) configured to be coupled with the first half chamber (11, 111, 211) to form a hermetic chamber; a first moving device configured to move the second half chamber (15, 215) relative to the first half chamber (11, 111, 211) between a separated position and a coupled position, the second half chamber (15, 215) being separated from the first half chamber (11, 111, 211) at the separated position, and the second opening (15a, 215a) being in close contact with the first opening (11a, 211a) at the coupled position; a first volume adjusting body disposed in the second half chamber (15, 215), the first volume adjusting body 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 (15, 215) is located at the coupled position; and a vacuum pump connected to the hermetic chamber; wherein a clamp disposed on the drying table, the clamp having a fluid cylinder, the clamp configured to fix the workpiece to the drying table; a hollow housing disposed to be inserted into the first half chamber; a swivel shaft coupled with the drying table, the swivel shaft configured to rotate with the drying table inside the housing; an annular channel circumferentially located between the housing and the swivel shaft; a first channel located inside the housing to connect the working fluid source and the annular channel; and a second channel located inside the swivel shaft to connect the fluid cylinder and the annular channel.