Subcommittee on Nuclear Power in the JSME Code Committee has established Task on Fatigue Evaluation to study fatigue evaluation for LWR nuclear power generation components. ASME Boiler & Pressure Vessel Code, Section III has revised the design fatigue curves in air in 2009 Addenda. One objective of Task on Fatigue Evaluation is to develop design fatigue curves in air based on the state of the data and knowledge. In this paper, the status of study on design fatigue curve of austenitic stainless steels in air in the task is introduced. The mean curve of fatigue curve of austenitic stainless steels was developed and the design factors on stress (strain) and cycles were studied. A tentative design fatigue curve of austenitic stainless steels in air was prepared by using the mean curve and the design factors studied.