This invention provides a method and apparatus for fabricating semiconductor single crystals. By using the method of this invention, the temperature gradient of the single crystal being lifted can be easily controlled. The as-grown defect density can be reduced, and it is possible to manufacture high quality semiconductor single crystals with high oxidation-film breakdown strength. A shield cylinder is used for surrounding the semiconductor single crystal 7 being lifted, the shield cylinder is made to be of the telescopic type and consists of a first shield duct 4, a second shield duct 5, a third shield duct 6. A wire 8 wrapping around a wind-up reel 10 is engaged with the third shield duct 6, and the shield cylinder can be driven to extend or retract by rotating the wind-up reel 10. An ascend and descend rod 3 is connected with the first duct 4, and the shield cylinder can be driven to move upward or downward by lifting or lowering the ascend and descend rod 3. The wind-up reel 10 is driven to retract part of the shield cylinder so that the lapped portion of the shield cylinder keeps a predetermined portion of the semiconductor single crystal 7 being lifted warm, and the temperature gradient of the semiconductor single crystal 7 can be reduced when it passes through the zone whose temperature is within a range from 1000.degree. C. to 1200.degree. C.