The adhesive strength between substrate and sprayed coatings seems to be mainly due to the mechanical interlocking effect. The physical bonding of spray particles to the substrate is the second factor. In this paper, the bonding mechanisms of sprayed coatings were studied on basis of experiments with the substrate at different surface roughness. The substrate surface roughness was quantitatively evaluated using a surface roughness tester. The tensile adhesion strength test method was used to evaluate the adhesive properties. The relationship between surface roughness and adhesive strength was investigated. The adhesive strength of plasma sprayed coating decreased with an increase in substrate surface roughness, as the size of the grit particles for roughening increased. On the contrary, the adhesive strength of arc sprayed coating increased.