Recently, because the micro-machine is noticed and electronic equipments are made much lighter and smaller, the demand for micro materials is increasing. However the mechanical properties data of the micro materials obviously run short and the evaluation method of micro materials is different according to the researcher. Therefore, the establishment of the test method for the micro materials is very necessary. In this study, fatigue tests were carried out using SUS304 thin sheets with thicknesses of 20μm. The specimens were manufactured using electrical discharge machining (EDM). Except for EDM specimens, the specimens of whom the EDM surface was polished by alumina abrasives were prepared. As the results, it was seen that the fatigue lives of polishing specimens were longer than those of EDM specimens. The fatigue crack origins of polishing specimens were almost inclusion.
