Mechanical surface treatment using cavitation impact was proposed and it is called as “cavitation peening”. In order to demonstrate peening effect on improvement of wear resistance using cavitation peening, mass loss caused by wear was evaluated experimentally with and without cavitation peening. In the present paper, cavitation was produced by a cavitating jet and a submerged pulse laser. Although it was believed that impact induced by laser ablation was used for peening, impact induced bubble collapse which was generated after laser ablation was larger than that of laser ablation. It was revealed that both peening method using the cavitating jet and submerged pulse laser reduced mass loss due to wear.