Although impact induced by cavitation bubble collapse causes severe damage in hydraulic machineries, the impact can be utilized for the mechanical surface treatment of metallic materials in the same way as shot peening. The peening using cavitation impact is named as “cavitation peening”. In the paper, the concepts and key factors on cavitation peening are presented including mechanism of generation of cavitation by using a submerged water jet. The difference between cavitation peening and water jet peening was also demonstrated by measuring peening intensity such as arc height of metallic plate. In order to discuss the difference between improvement of fatigue strength of stainless steel by cavitation peening, water jet peening, shot peening and submerged laser peening, a plane bending fatigue test was carried out. The specimens were treated at various processing time by each peening method, and the optimum processing time at each peening methods was revealed, then the fatigue strength of stainless steel treated at the optimum processing time was evaluated. It was concluded that the fatigue strength at N = 107 of cavitation peening was highest followed by shot peening, submerged laser peening and finally water jet peening.