This paper describes development of a thermal mechanical fatigue testing machine for solders. Several researches studying on creep, low cycle fatigue and creep-fatigue for solders at constant temperature have been reported recently, but no or small number of studies on thermal mechanical fatigue of solders have been reported. It might be resulted from that suitable thermal mechanical fatigue testing machines, which can perform the test at temperatures applicable to solders, have not been developed. In this study, the thermal mechanical fatigue testing machine which can cover the test temperatures between 233K (–40°C) and 423K (150°C) is developed. Using the developed testing machine, thermal mechanical fatigue test for Sn-3.5Ag lead-free solder was carried out and an applicability of the testing machine is investigated. This study also discusses the obtained thermal mechanical fatigue life in comparing with data in low cycle fatigue test at constant temperature.