melt 13 and dissolved by raising the output of the heater 2 to try reproducing a silicon single crystal in the same conditions as in the aforementioned production of the single crystal in order to confirm how the condition of the occurrence of the dislocation of the single crystal changed afterwards depending on whether or not a horizontal magnetic field was applied when the single crystal with dislocations was dissolved these single crystals with dislocations were dissolved partly in the condition that a horizontal magnetic field remained applied to the melt and partly in the condition that no horizontal magnetic field was applied to the melt in both cases the flow rate and pressure of argon gas to be supplied to the chamber when the single crystal was dissolved were 130 l mm and 4000 pa respectively and the number of rotations of the crucible was 5 rpm the results of the pulled up samples at this time are shown in table 1 in table 1 the conventional examples a to d show the results when the single crystal with dislocations was dissolved in the condition that a horizontal magnetic field remained applied and the examples e and f of the present invention show the results when the single crystal with dislocations was dissolved in the condition that no with dislocation show the was applied to the melt as is clear from table 1 it is found that in the case of the conventional examples a to d a dislocation of the single crystal occurs in the step of forming the shoulder portion or in step of forming the body portion in the pulling of the single.