This paper reports on the mictrostructure-adhesion property relationship in Ni/3C-SiC ohmic contacts. The microstructures of the surface and the interface in the Ni/3C-SiC layers annealed at various temperatures were investigated using the X-ray scattering techniques. The adhesion of the Ni on the 3C-SiC surface was examined by the scratch tester in the acoustic emission-frictional force mode. The Ni/SiC layer annealed at 500 degreesC exhibits the highest surface roughness with the lowest interface roughness. The Ni/SiC adhesion force was shown to be decreased with the annealing temperature up to 500 degreesC. As the annealing temperature is higher than 500 degreesC, the domain size of the NiSi2 silicides is increased with enhancement of crystallinity. The crystallinity enhancement is attributed, presumably to the low mismatch of lattice constants between the silicide and 3C-SiC.