In order to determine the fine particle peening (FPP) conditions using particles of 10μm in diameter that could improve the fatigue strength, the hardness of FPP-treated specimens under different conditions was investigated. As results of hardness tests, the hardness of FPP-treated specimen under the condition of 30mm of nozzle distance which indicates the highest velocity of particles showed higher than that of one under the condition of 50mm of nozzle distance. Additionally, the hardness was increased with decreasing peening time. Furthermore, in order to clarify the effects of FPP using particles of 10μm on fatigue properties of A5056 aluminum alloy with three different peening time, fatigue tests were performed at room temperature using cantilever-type rotary bending fatigue testing machine. It was found that the fatigue strength was increased with decreasing peening time due to increasing surface hardness.