Scratching and indentation test on (0001) (Ga surface) of single-crystal gallium nitride (GaN) by spherically tipped (10μm radius) diamond is reported in this paper. GaN has attracted keen attention as a new material of electric and light emission devises. It can realize high power and high frequency electric devices and ultra violet∼blue high luminance light emitting device. High-precision processing, however, is difficult because of its hard and brittle properties. Thus basically processing properties of GaN is important for wafer processing. Radial crack initiation load is 0.75N and lateral crack initiates at 1.0N. And two indents under 25μm distance generate interference of cracks. In scratching test for [1120], radial crack and lateral crack initiation loads are 0.97N and 1.17N. These are about 5% higher load than other direction scratches. Proximity scratch test by 0.4N constant load (under crack initiation load) on 100μm× 500μm area achieves flat surface, with 0.012μm Ra and 0.122μm Ry.