In sheet metal forming, we can recognize most deformed states by using in-plane biaxial deformation and can predict the occurrence of fracture by a forming limit diagram. However, in the case of axially symmetric tensile specimens, it is known that the magnitude of hydrostatic stress or stress triaxiality largely affects the occurrence of fracture. In this study, we investigated the history of hydrostatic stress and stress triaxiality by using an axially symmetric tapered tensile specimen.