NOVELTY - The apparatus comprises: a chamber in which the process of growing a silicon single crystal ingot is performed; a crucible installed inside the chamber and filled with silicon melt; a heater provided for heating the crucible and installed in an interior side of the chamber; a first cooling tube; and a second cooling tube that cools the silicon single crystal ingot and is movably mounted on the interior of the chamber. Length of the second cooling tube is increased by decreasing the length of the first cooling tube.    USE - The apparatus is useful for growing a single silicon crystal ingot (claimed) in the manufacturing process of semiconductor device such as solar cell.    ADVANTAGE - The apparatus is capable of effectively improving the cooling rate of the ingot, and ensures rapid growth of the single silicon crystal ingot with improved productivity.    DETAILED DESCRIPTION - The apparatus comprises: a chamber in which the process of growing a silicon single crystal ingot is performed; a crucible installed inside the chamber and filled with silicon melt; a heater provided for heating the crucible and installed in an interior side of the chamber; a first cooling tube; and a second cooling tube that cools the silicon single crystal ingot and is movably mounted on the interior of the chamber. Length of the second cooling tube is increased by decreasing the length of the first cooling tube. The second cooling tube is a movable tube that moves up and down along an axial direction within the chamber. An elevating part is installed over an upper portion of the chamber. The elevating part comprises a hollow shaft combined with the second cooling tube in a bottom portion of the chamber. The apparatus further comprises a motor that rotates along an elevating axis of the chamber. The shaft is present in communication with a circulation space of the second cooling tube. An elevation side of the shaft supplies cooling water to a cooling water inlet. Another side of the shaft supplies the cooling water to a cooling water outlet. The cooling water inlet and outlet are present inside the second cooling tube. The second cooling tube comprises a thermal shield that prevents the heating of silicon melt. The thermal shield comprises a heat insulating material present between the second cooling tube and the shield.