Abstract: To precisely predict the distribution of densities and sizes of void defects comprising voids and inner wall oxide membranes in a single crystal. The computer-based simulation determines, at steps 1 to 7, the distribution of temperatures within a single crystal 14 growing from a melt 12 from the time of its pulling-up to the time of its completing cooling with due consideration paid to convection currents in the melt 12. The computer-based simulation, at steps 8 to 15, determines the density of voids considering the cooling process of the single crystal separated from the melt, that is, the pulling-up speed of the single crystal after the separation from the melt, and reflecting the effect of slow and rapid cooling of the single crystal in the result, and relates the radius of voids with the thickness of inner wall oxide membrane developed around the voids.