<p>Grit blasting for surface pretreatment treated before thermal spraying creates enough surface roughness which ensures a strong mechanical bond between coating and substrate. This treatment causes, however, to decrease the fatigue limit of substrate under repeated stress by approximately 3%. In this study, specimens made from JIS SS400 steel were got ready and shot peening and grit blasting were processed (the combined process specimen) for improving fatigue limit. The surface property of the specimens such as residual stress and surface roughness were examined and then the fatigue test of specimens were done. The compressive residual stress generating 30μm below the surface for the combined process specimens was larger than that of the grit blasted ones and roughly equal to that of the shot peened ones. The fatigue limit of the combined process specimens was increased by 9% compared with the grit blasted specimens and by approximately 5% compared with the specimens without any treatments. The experimental results show, therefore, the combined process improves both fatigue strength and macroscopic surface roughness for substrate.</p>