Silicon single crystal substrates having uniform resistance, few BMDs in a surface layer and a moderate number of BMDs in a center of thickness of the substrate are formed from Czochralski silicon single crystals. The substrates have a resistivity in the center of a first main surface not lower than 50 Ω·cm and a rate of change in resistivity in the first main surface not higher than 3%, an average density of bulk micro defects in a region between the first main surface and a plane at a depth of 50 μm of less than 1×108/cm3, and an average density of bulk micro defects in a region lying between a plane at a depth of 300 μm and a plane at a depth of 400 μm from the first main surface not lower than 1×108 /cm3 and not higher than 1×109 /cm3.