In an X-ray topography image for a crystal growth main surface of a single-crystal diamond, a group of crystal defect points are gathered, each of the crystal defect points being a tip point of a crystal defect line reaching the crystal growth main surface, the crystal defect line representing a line in which a crystal defect exists. Further, in the single-crystal diamond, a plurality of crystal defect line-like gathered regions exist in parallel. In the plurality of crystal defect line-like gathered regions, groups of crystal defect points are gathered to extend in the form of lines in a direction angled by not more than 30° relative to one arbitrarily specified direction. Accordingly, a single-crystal diamond is provided which is used suitably for a cutting tool, a polishing tool, an optical component, an electronic component, a semiconductor material, and the like.