An apparatus for growing a silicon ingot including a graphite crucible in which a quartz crucible is placed, a driving axis connected to a lower part of the graphite crucible to revolve and move the graphite crucible up and down so as to support the graphite crucible, a heating element to heat the graphite crucible, and an insulating wall to protect and thermally isolate the graphite crucible, heating means, and driving axis in part from the external environment. The driving axis includes a hollow axis part having a hollow inside, an insulating axis part attached to the bottom of the hollow axis part to inhibit heat transfer, and a cylindrical axis part attached to the bottom of the insulating axis part. The construction of the driving axis reduces a temperature gradient in the molten silicon, improving uniform heat distribution for increased silicon ingot quality.