It is an advanced automatic stress measurement device that measures the retardation which displays birefringence phenomenon under polarized light. The light travels through the polarizer to become circular polarized light. When the stressed sample is placed, the slow and fast axis of birefringence produces the retardation, and the outgoing light becomes elliptical polarized light. Through the phase retarder and polarization camera, the phase and axial angle change of the polarized light under the influence of stress are measured, thus calculating the sample stress value and the slow/fast axis direction.