The invention provides a high-quality SiC single-crystal substrate, a seed crystal for producing the high-quality SiC single-crystal substrate, and a method of producing the high-quality SiC single-crystal substrate, which enable improvement of device yield and stability. Provided is an SiC single-crystal substrate wherein, when the SiC single-crystal substrate is divided into 5-mm square regions, such regions in which dislocation pairs or dislocation rows having intervals between their dislocation end positions of 5 μm or less are present among the dislocations that have ends at the substrate surface account for 50% or less of all such regions within the substrate surface and the dislocation density in the substrate of dislocations other than the dislocation pairs or dislocation is 8,000/cm2.