This invention provides a polycrystalline gallium-nitride self-supporting substrate comprising a plurality of gallium-nitride-based single-crystal grains aligned to a specific crystal orientation in adirection that is substantially parallel to the normal direction. The crystal orientations of said gallium-nitride-based single-crystal grains, as measured by subjecting the surface of the self-supporting substrate to electron backscatter diffraction (EBSD) and performing inverse-pole-figure mapping, form a variety of angles with the aforementioned specific crystal orientation, and the mean valueof the distribution of said angles is between 1 degree and 10 degrees, inclusive. This light-emitting element comprises the abovementioned self-supporting substrate and a light-emitting functional layer that is formed on top of the substrate and contains one or more layers each comprising a plurality of semiconductor single-crystal grains each exhibiting a single-crystal structure that is substantially parallel to the normal direction. This invention makes it possible to provide a polycrystalline gallium-nitride self-supporting substrate with a reduced defect density in the surface thereof. Alight-emitting element that uses said polycrystalline gallium-nitride self-supporting substrate and exhibits a high luminous efficacy can also be obtained.