This paper describes the development of triaxial tension creep machine. The developed machine can make equitriaxial tension creep experiments, and has a loading capacity of 49KN and the maximum temperature of 923K. Three dimensional finite element (FE) elastic-creep analyses were made to determine the shape and dimension of the specimen having uniform equi-triaxial stress distribution at the specimen center. The specimen shape determined by the FE analyses has 2.0mm groove radius at the notch. Equi-triaxial tension creep test was performed using Type 304 specimen at 923K. The uniaxial, equi-biaxial and equi-triaxial tension creep lives of Type 304 stainless steel at 923K were compared. Creep rupture time increased with increasing J1(=σx+σy+σz), so that the positive mean stress has an effect of increasing the rupture time. In the equi-triaxial tension stress condition, three principal strains of εx, εy and εz were smaller than in the uniaxial tension and equi-biaxial tension stressing conditions.