The diffuse x‐ray scattering due to small defects in a silicon single crystal, which has been found by Yasuami, Harada, and Wakamatsu [J. Appl. Phys. 50, 6860 (1979)] has been identified as coming from a thin surface layer of the crystal. The small defects, therefore, cannot be B‐swirl defects and do not have any correlation with crystal growth methods, floating zone or Czochralski zone, and with growth direction. They are considered to be introduced during the surface polishing process and to exist in the surface layer of about 150 &mgr;m thick. For detecting such small defects, diffuse x‐ray scattering is more advantageous than the conventional rocking curve measurement.