The present invention is a process for the production of a single crystal by means of an FZ process, that rotate the formation of a melting zone by melting a raw material-crystal ingot with an induction heat coil and moving the melting zone by lowering the raw material-crystal ingot on an upper side and a single crystal ingot on a lower side relative to the induction heat coil, for growing the single crystal ingot, including the process: a measurement step of the weight of a remaining raw material crystal ingot,when growth is stopped during crystal growth and the production of a single crystal is stopped; an assessment step of the calculation of a theoretical yield of a straight crystal body that can be produced from the remaining raw material crystal ingot and of the determination of a maximum diameter of a single crystal that can be produced again, or of the determination not to produce a single crystal; and a re-production step of the re-production of a single crystal, if the maximum diameter of the single crystal that can be re-produced,is determined. This provides a process for the production of a single crystal that suppresses the deterioration of yields by effectively using the remaining raw material crystal ingot when the crystal growth is stopped in the middle.
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