An embodiment comprises: a chamber; a crucible provided in the chamber and accommodating a molten liquid which is a raw material for single crystal growth; a crucible screen disposed on the upper end of the crucible; and a moving unit for raising or lowering the crucible screen, wherein the crucible screen and a first upper adiabatic unit are raised to control the stroke distance, thereby preventing the impossibility of a lift-off process caused by a shortage of the stroke distance and the generation of cracks in single crystals.