Abstract: A method of and an apparatus for predicting density and distribution of crystal defects those would appear in a semiconductor wafer in the course during heat treatment thereof on the basis of respective densities and distributions of interstitial atoms and atom vacancies frozen, during crystal growth, into a semiconductor single crystal which is used as a raw material of said semiconductor wafer, in a section of said semiconductor single crystal corresponding to said semiconductor wafer, comprising: deriving said respective densities and distributions of interstitial atoms and atom vacancies from a first diffusion equation representing a change with time in concentration of interstitial atoms in the semiconductor single crystal in the course of growth from a melt as a function of a position in the crystal and a second diffusion equation representing a change with time in concentration of atom vacancies in said crystal as a function of a position in the crystal.